params: Add documentation for array query param and query params

Author: BenjD90

README.md

@@ -378,6 +378,28 @@ getUsers(@QueryParam("limit") limit: number) {
 }
 ```
 
+You can use `isArray` option to get a query param array. This will cast the query param :
+
+```typescript
+@Get("/users/by-multiple-ids")
+getUsers(@QueryParam("ids", { isArray: true}) ids: string[]) {
+}
+```
+
+`GET /users/by-multiple-ids?ids=a` → `ids = ['a']`
+`GET /users/by-multiple-ids?ids=a&ids=b` → `ids = ['a', 'b']`
+
+You can combine use `isArray` option with `type` option to get a query param array of one type. This will cast the query param :
+
+```typescript
+@Get("/users/by-multiple-ids")
+getUsers(@QueryParam("ids", { isArray: true, type: Number}) ids: number[]) {
+}
+```
+
+`GET /users/by-multiple-ids?ids=1` → `ids = [1]`
+`GET /users/by-multiple-ids?ids=1&ids=3.5` → `ids = [1, 3.5]`
+
 If you want to inject all query parameters use `@QueryParams()` decorator.
 The bigest benefit of this approach is that you can perform validation of the params.
 
@@ -402,12 +424,17 @@ class GetUsersQuery {
     @IsBoolean()
     isActive: boolean;
 
+    @IsArray()
+    @IsNumber(undefined, { each: true })
+    @Type(() => Number)
+    ids: number[];
 }
 
 @Get("/users")
 getUsers(@QueryParams() query: GetUsersQuery) {
     // here you can access query.role, query.limit
     // and others valid query parameters
+    // query.ids will be an array, of numbers, even with one element
 }
 ```
 
@@ -1535,7 +1562,7 @@ export class QuestionController {
 
 | Signature                                                        | Example                                           | Description                                                                                                                                 |
 | ---------------------------------------------------------------- | ------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- |
-| `@Authorized(roles?: string\|string[])`                          | `@Authorized("SUPER_ADMIN")` get()                | Checks if user is authorized and has given roles on a given route. `authorizationChecker` should be defined in routing-controllers options. |  |
+| `@Authorized(roles?: string\|string[])`                          | `@Authorized("SUPER_ADMIN")` get()                | Checks if user is authorized and has given roles on a given route. `authorizationChecker` should be defined in routing-controllers options. |
 | `@CurrentUser(options?: { required?: boolean })`                 | get(@CurrentUser({ required: true }) user: User)  | Injects currently authorized user. `currentUserChecker` should be defined in routing-controllers options.                                   |
 | `@Header(headerName: string, headerValue: string)`               | `@Header("Cache-Control", "private")` get()       | Allows to explicitly set any HTTP header returned in the response.                                                                          |
 | `@ContentType(contentType: string)`                              | `@ContentType("text/csv")` get()                  | Allows to explicitly set HTTP Content-Type returned in the response.                                                                        |