[KZL-907] Getting started dev plugin (#276)

## What does this PR do?

This PR responds to this [ticket](https://jira.kaliop.net/browse/KZL-907).
Also, it increases the readability of documentation's plugin part.

### How should this be manually tested?

[Netify](https://deploy-preview-276--kuzzle-doc-v2.netlify.com/plugins/1/essentials/introduction/)

### Other changes

- Re-arrange plugin documentation path
- Update dead link in boilerplate repository

### Boyscout

Prettier

Author: Yoann-Abbes

src/guide/1/essentials/plugins/index.md

@@ -12,31 +12,31 @@ For example, imagine you are developing a mobile application that accesses a **t
 
 Kuzzle's **[Plugin Engine]({{ site_base_path }}plugins/1)** is a powerful feature that ensures that Kuzzle meets any project requirement:
 
-* select from a set of prebuilt plugins (such as the [OAuth2 Authentication Plugin](https://github.com/kuzzleio/kuzzle-plugin-auth-passport-oauth) or the [MQTT Protocol](https://github.com/kuzzleio/protocol-mqtt)).
-* [create your own plugin]({{ site_base_path }}plugins/1/essentials) to meet your specific requirements.
+- select from a set of prebuilt plugins (such as the [OAuth2 Authentication Plugin](https://github.com/kuzzleio/kuzzle-plugin-auth-passport-oauth) or the [MQTT Protocol](https://github.com/kuzzleio/protocol-mqtt)).
+- [create your own plugin]({{ site_base_path }}plugins/1/essentials) to meet your specific requirements.
 
 ---
 
 ## Plugins
 
 Plugins are used to extend Kuzzle's functionalities. They are loaded into Kuzzle during startup and share its execution thread. A plugin can implement one or multiple of the following interfaces:
 
-[Hooks]({{ site_base_path }}plugins/1/essentials/hooks): adds asynchronous listeners that perform operations triggered by data events. When a listened event occurs, the data is sent to the listeners and Kuzzle continues its process without waiting for the listener to complete.
+[Hooks]({{ site_base_path }}plugins/1/hooks): adds asynchronous listeners that perform operations triggered by data events. When a listened event occurs, the data is sent to the listeners and Kuzzle continues its process without waiting for the listener to complete.
 
-  _Example - "Write a log to a third-party logging service every time a document is deleted"_. The [Logger Plugin](https://github.com/kuzzleio/kuzzle-plugin-logger) (shipped with Kuzzle) uses this feature to log all the data-related events.
+_Example - "Write a log to a third-party logging service every time a document is deleted"_. The [Logger Plugin](https://github.com/kuzzleio/kuzzle-plugin-logger) (shipped with Kuzzle) uses this feature to log all the data-related events.
 
-[Pipes]({{ site_base_path }}plugins/1/essentials/pipes): adds synchronous listeners that perform operations triggered by data events. When a listened event occurs, the data is passed synchronously to listeners, each modifying the input data and returning the result to the next listener. Kuzzle waits until the last listener completes and returns its data. If any  listener returns an error, it will interrupt the Kuzzle lifecycle, and the thrown error will be used as a response by Kuzzle.
+[Pipes]({{ site_base_path }}plugins/1/pipes): adds synchronous listeners that perform operations triggered by data events. When a listened event occurs, the data is passed synchronously to listeners, each modifying the input data and returning the result to the next listener. Kuzzle waits until the last listener completes and returns its data. If any listener returns an error, it will interrupt the Kuzzle lifecycle, and the thrown error will be used as a response by Kuzzle.
 
-  _Example - "Compare the ordered quantity with the available stock and return an error if the amount of ordered items exceeds the amount in stock"_.
+_Example - "Compare the ordered quantity with the available stock and return an error if the amount of ordered items exceeds the amount in stock"_.
 
-[Controllers]({{ site_base_path }}plugins/1/essentials/controllers): extends Kuzzle API.
+[Controllers]({{ site_base_path }}plugins/1/controllers): extends Kuzzle API.
 
-  _Example - "Expose a `checkout` API endpoint that handles a third-party payment process"_.
+_Example - "Expose a `checkout` API endpoint that handles a third-party payment process"_.
 
 [Strategies]({{ site_base_path }}plugins/1/essentials/strategies): add an authentication strategy to identify and authenticate users.
 
-  _Example - "Enable OAuth based authentication in Kuzzle"_
-  Kuzzle ships with the [Local Strategy Plugin](https://github.com/kuzzleio/kuzzle-plugin-auth-passport-local) and thanks to PassportJS, more than 300 authentication strategies are readily available.
+_Example - "Enable OAuth based authentication in Kuzzle"_
+Kuzzle ships with the [Local Strategy Plugin](https://github.com/kuzzleio/kuzzle-plugin-auth-passport-local) and thanks to PassportJS, more than 300 authentication strategies are readily available.
 
 ## Protocols
 
@@ -61,10 +61,8 @@ Prior to loading the plugin into Kuzzle, you will need to load all of the plugin
 
 To demonstrate, we are going to install the [**Plugin Boilerplate**](https://github.com/kuzzleio/kuzzle-core-plugin-boilerplate), a plugin example that uses all features available to a plugin.
 
-
 Go to the Kuzzle installation folder and type:
 
-
 ```bash
 # Open plugins/available folder
 cd plugins/available
@@ -105,13 +103,8 @@ Once Kuzzle has restarted, check the server information at `http://localhost:751
               "document:beforeUpdate",
               "core:overload"
             ],
-            "pipes": [
-              "document:beforeCreate",
-              "realtime:beforePublish"
-            ],
-            "controllers": [
-              "kuzzle-core-plugin-boilerplate/myNewController"
-            ],
+            "pipes": ["document:beforeCreate", "realtime:beforePublish"],
+            "controllers": ["kuzzle-core-plugin-boilerplate/myNewController"],
             "routes": [
               {
                 "verb": "get",
@@ -126,9 +119,7 @@ Once Kuzzle has restarted, check the server information at `http://localhost:751
                 "action": "myNewAction"
               }
             ],
-            "strategies": [
-              "dummy"
-            ]
+            "strategies": ["dummy"]
           }
         }
       }
@@ -138,13 +129,13 @@ Once Kuzzle has restarted, check the server information at `http://localhost:751
 ```
 
 Note that the plugin description above contains a property for each plugin component:
+
 - `hooks` asynchronous operations that depend on data-related events
 - `pipes` synchronous operations that depend on data-related events
 - `controllers` list of exposed actions in the API
 - `routes` list of exposed actions in the **REST** API
 - `strategies` list of exposed authentication strategies
 
-
 ---
 
 ## Installing protocols
@@ -179,6 +170,7 @@ ln -s ../available/protocol-mqtt .
 To get more insight into how plugins work, please refer to the [Plugin Reference]({{ site_base_path }}plugins/1).
 
 Here is a list of official plugins:
+
 - [**kuzzle-plugin-auth-passport-local**](https://github.com/kuzzleio/kuzzle-plugin-auth-passport-local): authentication Plugin shipped with Kuzzle
 - [**kuzzle-plugin-logger**](https://github.com/kuzzleio/kuzzle-plugin-logger): plugin shipped with Kuzzle
 - [**kuzzle-plugin-auth-passport-oauth**](https://github.com/kuzzleio/kuzzle-plugin-auth-passport-oauth): authentication plugin

src/plugins/1/accessors/trigger/index.md

@@ -9,23 +9,22 @@ title: trigger
 
 Triggers a custom event.
 
-This allows interactions with other plugins using [hooks]({{ site_base_path }}plugins/1/essentials/hooks/) or [pipes]({{ site_base_path }}plugins/1/essentials/pipes/).
+This allows interactions with other plugins using [hooks]({{ site_base_path }}plugins/1/hooks/) or [pipes]({{ site_base_path }}plugins/1/pipes/).
 
 ## Arguments
 
 ```js
-trigger(event, [payload])
+trigger(event, [payload]);
 ```
 
 <br/>
 
-| Arguments | Type | Description |
-|-----------|------|-------------|
-| `event` | <pre>string</pre> | Custom event name |
-| `payload` | <pre>object</pre> | Event payload |
+| Arguments | Type              | Description       |
+| --------- | ----------------- | ----------------- |
+| `event`   | <pre>string</pre> | Custom event name |
+| `payload` | <pre>object</pre> | Event payload     |
 
-
-**Note:** the triggered event is renamed using the following format:<br/>`plugin-<plugin name>:<event>`. 
+**Note:** the triggered event is renamed using the following format:<br/>`plugin-<plugin name>:<event>`.
 
 ## Example
 
@@ -37,13 +36,13 @@ context.accessors.trigger('someEvent', {
 
 // Listening plugin
 class ListeningPlugin {
-  constructor () {
+  constructor() {
     this.hooks = {
       'plugin-some-plugin:someEvent': 'someEventListener'
     };
   }
 
-  someEventListener (payload) {
+  someEventListener(payload) {
     this.doSomething(payload);
   }
 }

src/plugins/1/essentials/controllers/index.md renamed to src/plugins/1/controllers/Documentation/index.md

@@ -1,14 +1,14 @@
 ---
 layout: full.html.hbs
-title: Controllers
+title: Documentation
 order: 400
 ---
 
 # Controllers
 
 Kuzzle's API is divided into controllers, each exposing executable actions (see [API reference]({{ site_base_path }}api/1/essentials/query-syntax)).
 
-Plugins can extend Kuzzle's API by adding new controllers to it. 
+Plugins can extend Kuzzle's API by adding new controllers to it.
 
 [Security access]({{ site_base_path }}guide/1/essentials/security/) to plugin controllers must be given (or denied), using the exact same way as with native API controllers.
 
@@ -21,7 +21,7 @@ To avoid naming conflicts, Kuzzle prefixes plugin controllers names with the plu
 ### HTTP
 
 ```http
-URL: http://<server>:<port>/_plugin/<plugin name>/<url defined by the plugin>/<resources> 
+URL: http://<server>:<port>/_plugin/<plugin name>/<url defined by the plugin>/<resources>
 Method: <verb defined by the plugin>
 ```
 
@@ -53,16 +53,17 @@ Kuzzle normalizes [queries]({{ site_base_path }}api/1/essentials/query-syntax) i
 
 Quick summary of how queries are normalized:
 
-* HTTP:
-  * dynamic arguments provided in the URL, and query string arguments are stored in `request.input.args`
-  * the body content is made available in `request.input.body`
-  * if the URL contains an `index`, a `collection` or a `_id` argument, it will be stored in `request.input.resource`
-  * request headers can be found in `request.context.connection.misc.headers`
+- HTTP:
 
-* Other protocols:
-  * the `body` property is stored in `request.input.body`
-  * these root properties are available in `request.input.resource`: `index`, `collection`, `_id`
-  * any other properties at the root of the query object will be stored in `request.input.args`
+  - dynamic arguments provided in the URL, and query string arguments are stored in `request.input.args`
+  - the body content is made available in `request.input.body`
+  - if the URL contains an `index`, a `collection` or a `_id` argument, it will be stored in `request.input.resource`
+  - request headers can be found in `request.context.connection.misc.headers`
+
+- Other protocols:
+  - the `body` property is stored in `request.input.body`
+  - these root properties are available in `request.input.resource`: `index`, `collection`, `_id`
+  - any other properties at the root of the query object will be stored in `request.input.args`
 
 ---
 
@@ -78,7 +79,7 @@ Read more about these automatic controller events [here]({{ site_base_path }}plu
 
 ```javascript
 module.exports = class ControllerPlugin {
-  constructor () {
+  constructor() {
     /*
       Adds a new "newController" controller to Kuzzle's API.
 
@@ -128,16 +129,26 @@ module.exports = class ControllerPlugin {
       property
      */
     this.routes = [
-      {verb: 'get', url: '/foo/:name', controller: 'newController', action: 'myAction'},
-      {verb: 'post', url: '/bar', controller: 'newController', action: 'myOtherAction'}
+      {
+        verb: 'get',
+        url: '/foo/:name',
+        controller: 'newController',
+        action: 'myAction'
+      },
+      {
+        verb: 'post',
+        url: '/bar',
+        controller: 'newController',
+        action: 'myOtherAction'
+      }
     ];
   }
 
   /*
     Required plugin initialization function
     (see the "Plugin prerequisites" section)
    */
-  init (customConfig, context) {
+  init(customConfig, context) {
     // plugin initialization
   }
 
@@ -148,17 +159,20 @@ module.exports = class ControllerPlugin {
     This result can be of any JS type (scalar, object, array), and
     will be used to build a response to send to the requesting client
    */
-  actionFunction (request) {
+  actionFunction(request) {
     // do action
 
     // optional: set network specific headers
     if (request.context.protocol === 'http') {
       // expires in 1h
-      request.response.setHeader('expires', new Date(Date.now() + 3600000).toUTCString());
+      request.response.setHeader(
+        'expires',
+        new Date(Date.now() + 3600000).toUTCString()
+      );
     }
 
     // Resolve with the result content. For instance:
-    return Promise.resolve({acknowledge: true});
+    return Promise.resolve({ acknowledge: true });
   }
 
   /*
@@ -168,9 +182,9 @@ module.exports = class ControllerPlugin {
     This result can be of any JS type (scalar, object, array), and
     will be used to build a response to send to the requesting client
    */
-  otherActionFunction (request) {
+  otherActionFunction(request) {
     // do action
     return Promise.resolve(/* result content */);
   }
-}
+};
 ```

src/plugins/1/controllers/index.md

@@ -0,0 +1,5 @@
+---
+layout: full.html.hbs
+title: Controllers
+order: 4
+---