Updated docs for authentication feature in pages

Author: cirykpopeye

03. user guide/03. pages.md

@@ -48,6 +48,12 @@ Sometimes you want a menu item to go to an external website or another internal
 
 ![Redirect](https://github.com/forkcms/documentation/raw/master/03.%20user%20guide/assets/pages_redirect.png)
 
+### Authentication
+
+This tab will only be shown when the profiles module is installed. Sometimes you would like to have only logged in users to view specific pages, or even specific groups. This is now possible within the authentication tab. When enabling user authentication this page will be hidden from the navigation and can not be visited by a non-authenticated user. When you have created groups within the profiles module and once you enabled user authentication you'll have the option to limit access depending on the profiles group.
+
+![Authentication](https://github.com/forkcms/documentation/raw/master/03.%20user%20guide/assets/pages_authentication.png)
+
 ### Settings
 
 At the settings page you are able to change the basic properties of your page. The first options let you hide the page. The use this page as module-action can be check if you link a sub-action directly to a page. For instance if you want a custom template for the detail of a blog post.