Add Oauth and Graphql sections

docs/en/features/oauth.md

@@ -0,0 +1,30 @@
+# OAuth
+
+You can configure authentication services with external OAuth suppliers, right now Twitter, Facebook and Google are supported.
+
+## 1. Create an App on the platform 
+For each platform, go to their developers section and follow their guides to create an app.
+
+## 2. Set your CONSUL's url
+
+They'll ask you for your CONSUL's auth URL, and as you can see running `rake routes` at your CONSUL repo locally:
+  ```bash
+user_omniauth_authorize GET|POST /users/auth/:provider(.:format)          users/omniauth_callbacks#passthru {:provider=>/twitter|facebook|google_oauth2/}
+```
+
+So for example the URL for facebook application would be `yourdomain.com/users/auth/facebook.json`
+
+## 3. Set key & secret values
+
+When you complete the application registration you'll get a *key* and *secret* values, those need to be stored at your `config/secrets.yml` file:
+
+```yml
+  twitter_key: ""
+  twitter_secret: ""
+  facebook_key: ""
+  facebook_secret: ""
+  google_oauth2_key: ""
+  google_oauth2_secret: ""
+```
+
+*NOTE:* Also in the case of Google, verify that the APIs *Contacts API* and *Google+ API* are enabled for the application.