minor #3669 Fixed syntax highlighting (rvanlaarhoven)

This PR was merged into the master branch.

Discussion
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Fixed syntax highlighting

Fixed syntax highlighting for the PostVoter example

Commits
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484b7b9 Added :
7eb3051 Fixed syntax highlighting

Author: weaverryan

cookbook/security/voters_data_permission.rst

@@ -54,7 +54,9 @@ Creating the Custom Voter
 -------------------------
 
 The goal is to create a voter that checks if a user has access to view or
-edit a particular object. Here's an example implementation::
+edit a particular object. Here's an example implementation:
+
+.. code-block:: php
 
     // src/Acme/DemoBundle/Security/Authorization/Voter/PostVoter.php
     namespace Acme\DemoBundle\Security\Authorization\Voter;