add social network authentication doc

docs/helpful-guides/social-network-authentication.md

@@ -0,0 +1,58 @@
+Social Network Authentication
+=============================
+
+If you wish to add user registration and login throughout social networks the first thing you need to do is to add the 
+official [Yii's auth client extension](https://github.com/yiisoft/yii2-authclient) to your application. The preferred 
+way to install is through [composer](http://getcomposer.org/download/).
+
+Either run
+
+```
+composer require --prefer-dist yiisoft/yii2-authclient
+```
+
+or add
+
+```json
+"yiisoft/yii2-authclient": "~2.1.0"
+```
+
+to the `require` section of your composer.json.
+
+After you need to configure the `authClientCollection::clients` on your Application `components` section: 
+
+```php 
+// ... 
+'components' => [
+    // ...
+    'authClientCollection' => [
+        'class' => 'yii\authclient\Collection',
+        'clients' => [
+            'facebook' => [
+                'class' => 'Da\User\AuthClient\Facebook',
+                'clientId' => 'facebook_client_id',
+                'clientScret' => 'facebook_client_secret'
+            ]
+        ]
+    ]
+]
+```
+
+We have override the clients that come with Yii official's auth extension so to provide them with a signature that 
+would help us access the email and username with ease. 
+
+The following is the list of clients supported by the module: 
+
+- Facebook - 'Da\User\AuthClient\Facebook'
+- Github - 'Da\User\AuthClient\Github'
+- Google - 'Da\User\AuthClient\Google'
+- LinkedIn - 'Da\User\AuthClient\LinkedIn'
+- Twitter - 'Da\User\AuthClient\Twitter'
+- VKontakte - 'Da\User\AuthClient\VKontakte'
+- Yandex - 'Da\User\AuthClient\Yandex'
+
+For further information about how to configure the clients, please visit the 
+[Official Yii Auth Client Extension documentation](https://github.com/yiisoft/yii2-authclient/blob/master/docs/guide/installation.md).
+
+
+© [2amigos](http://www.2amigos.us/) 2013-2017

docs/index.md

@@ -143,6 +143,7 @@ Helpful Guides
 --------------
 
 - [Separate Frontend and Backend Sessions](helpful-guides/separate-frontend-and-backend-sessions.md)
+- [Social Network Authentication](helpful-guides/social-network-authentication.md)
 
 Contributing
 ------------