Improve jsdoc for API return values (#3327)

* Add jsdoc for usePromises, add @link for callbacks

* Update petstore samples

* Improve jsdoc for void return type + usePromises

* Add back curly brackets correctly in model template

* Add link to Promise doc in jsdoc comment

* Fix jsdoc annotation for callApi method

The return type annotation was also broken here.

samples/client/petstore/javascript-promise/docs/FakeApi.md

@@ -4,53 +4,10 @@ All URIs are relative to *http://petstore.swagger.io/v2*
 
 Method | HTTP request | Description
 ------------- | ------------- | -------------
-[**testCodeInjectEnd**](FakeApi.md#testCodeInjectEnd) | **PUT** /fake | To test code injection  =end
 [**testEndpointParameters**](FakeApi.md#testEndpointParameters) | **POST** /fake | Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
 [**testEnumQueryParameters**](FakeApi.md#testEnumQueryParameters) | **GET** /fake | To test enum query parameters
 
 
-<a name="testCodeInjectEnd"></a>
-# **testCodeInjectEnd**
-> testCodeInjectEnd(opts)
-
-To test code injection  &#x3D;end
-
-### Example
-```javascript
-var SwaggerPetstore = require('swagger_petstore');
-
-var apiInstance = new SwaggerPetstore.FakeApi();
-
-var opts = { 
-  'testCodeInjectEnd': "testCodeInjectEnd_example" // String | To test code injection  =end
-};
-apiInstance.testCodeInjectEnd(opts).then(function() {
-  console.log('API called successfully.');
-}, function(error) {
-  console.error(error);
-});
-
-```
-
-### Parameters
-
-Name | Type | Description  | Notes
-------------- | ------------- | ------------- | -------------
- **testCodeInjectEnd** | **String**| To test code injection  &#x3D;end | [optional] 
-
-### Return type
-
-null (empty response body)
-
-### Authorization
-
-No authorization required
-
-### HTTP request headers
-
- - **Content-Type**: application/json, */ =end));(phpinfo(
- - **Accept**: application/json, */ end
-
 <a name="testEndpointParameters"></a>
 # **testEndpointParameters**
 > testEndpointParameters(_number, _double, _string, _byte, opts)