Add a plugin description in README (#11)

Author: Nitive

README.md

@@ -1,12 +1,75 @@
 # helm-deno
 
-> **⚠️ Work in progress, breaking changes are to be expected ⚠️**  
-> There is also no documentation yet but we'll write some in upcoming weeks
-
 helm-deno allows write helm charts with JavaScript and TypeScript
 
+## ️Project status: Alpha️
+
+Project currently in its early stage. Breaking changes are to be expected. Please read [changelog](https://github.com/CSSSR/helm-deno/releases) before upgrade.
+
+- [Known bugs](https://github.com/CSSSR/helm-deno/issues?q=is%3Aopen+is%3Aissue+label%3A%22issue+is+bug%22)
+- [Missign features](https://github.com/CSSSR/helm-deno/issues?q=is%3Aopen+is%3Aissue+label%3A%22priority+4+%28must%29%22)
+- [Expected breaking changes](https://github.com/CSSSR/helm-deno/issues?q=is%3Aopen+is%3Aissue+label%3A%22issue+is+breaking+suggestion%22+label%3A%22priority+4+%28must%29%22)
+
+## Features
+
+- Write charts in JavaScript and TypeScript
+- Easy to extend with deno modules
+- Can be used with helm-secrets, helm-diff and helm-push
+
+## What deno is?
+
+Deno is a simple, modern and secure runtime for JavaScript and TypeScript that uses V8 and is built in Rust. Learn more on [Deno official website](https://deno.land).
+
+## Installation
+
+```sh
+helm plugin install https://github.com/CSSSR/helm-deno
+```
+
+There is no need to install Deno, it will be installed automatically.
+
+## Getting started
+
+```sh
+helm deno create chart-name # TODO: currently does not work (issue #10)
+```
+
+It will create a directory structure that looks
+something like this:
+
+```
+chart-name/
+├── .helmignore     # Contains patterns to ignore when packaging Helm charts.
+├── Chart.yaml      # Information about your chart
+├── values.yaml     # The default values for your templates
+└── deno-templates/ # The template files
+    ├── mod.ts
+    └── resources/
+        ├── deployment.ts
+        ├── service.ts
+        └── ingress.ts
+```
+
+Render templates and print the result
+
+```sh
+helm deno template my-release chart-name/
+```
+
+## Use cases
+
+We have written this plugin because we wasn't happy with default helm's templates system: Go templates. There is some of things which wasn't possible with it or was too complex to deal with.
+
+**Working with data structures, not templates.** Programming languages are much more suitable for working with data such as kubernetes objects. And using functions instead of `define` and `template` is so much simpler.
+**Modules.** Deno has a big set of [standard](https://deno.land/std) and [third-party](https://deno.land/x) modules. Publishing your own modules is as easy as pushing file to git repository or serving static files.
+**Type System and static analysis.** Types for your chart values is a good documentaion which is always up-to-date. You are also safe from errors like typos and using variables that do not exist.
+**Ability to work with file system and network.** You can replace kubernetes operators or helm plugins with just a function. For example, decode a sops-encrypted file or fetch secrets from Hashicorp Vault.
+
 ## Current limitations
 
 - Does not support passing options via equal sign `--values=values-file.yaml`
 - Require strict order of command-line arguments: `helm deno <secrets> <diff> upgrade/template/install [RELEASE] [CHART] <flags>`
-- helm-deno was not tested on Windows but it should probably works
+- Does not support `--reuse-values`
+- Slower that go templates
+- Possible have bugs: doesn't have much tests yet
+- Was not tested on Windows but it should probably works