Add versionadded tag to security config reference, reference cookbok …

…entry in book

book/security.rst

@@ -152,8 +152,8 @@ Let's look briefly at how security works and how each part of the configuration
 comes into play.
 
 .. versionadded:: 2.4
-    A new property was added to the firewall configuration, where you can 
-make a restriction, called ``host``.
+    Support for restricting security firewalls to a specific host was added in
+    Symfony 2.4.
 
 How Security Works: Authentication and Authorization
 ----------------------------------------------------
@@ -1102,7 +1102,7 @@ Thanks to the SensioFrameworkExtraBundle, you can also secure your controller us
         // ...
     }
 
-For more information, see the 
+For more information, see the
 :doc:`FrameworkExtraBundle documentation </bundles/SensioFrameworkExtraBundle/annotations/security>`.
 
 Securing other Services
@@ -2168,6 +2168,7 @@ Learn more from the Cookbook
 * :doc:`Blacklist users by IP address with a custom voter </cookbook/security/voters>`
 * :doc:`Access Control Lists (ACLs) </cookbook/security/acl>`
 * :doc:`/cookbook/security/remember_me`
+* :doc:`How to Restrict Firewalls to a Specific Host </cookbook/security/host_restriction>`
 
 .. _`FOSUserBundle`: https://github.com/FriendsOfSymfony/FOSUserBundle
 .. _`implement the \Serializable interface`: http://php.net/manual/en/class.serializable.php

reference/configuration/security.rst

@@ -13,6 +13,10 @@ Full Default Configuration
 The following is the full default configuration for the security system.
 Each part will be explained in the next section.
 
+.. versionadded:: 2.4
+    Support for restricting security firewalls to a specific host was added in
+    Symfony 2.4.
+
 .. configuration-block::
 
     .. code-block:: yaml