mark code as php code block

Author: alexander-schranz

Resources/doc/features/symfony-http-cache.rst

@@ -76,7 +76,9 @@ making your kernel capable of providing the cache.
 
 The recommended way to wire things up is to instantiate the cache kernel in the
 kernel constructor to guarantee consistent setup over all entry points. Adjust
-your kernel like this::
+your kernel like this:
+
+.. code-block:: php
 
     // src/AppKernel.php
 
@@ -100,6 +102,8 @@ your kernel like this::
 
 Now you need to adjust your front controller (that you set up according to the `Symfony HttpCache documentation_`) to use that cache instance rather than creating one:
 
+.. code-block:: php
+
     // public/index.php
 
     use App\AppKernel;