minor #7452 Added filename references to examples (RaitoCZ)

This PR was submitted for the 3.2 branch but it was merged into the 2.7 branch instead (closes #7452).

Discussion
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Added filename references to examples

Commits
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9c2fb45 Added filename references to examples

Author: xabbuh

routing/scheme.rst

@@ -11,14 +11,16 @@ the URI scheme via schemes:
 .. configuration-block::
 
     .. code-block:: yaml
-
+    
+        # app/config/routing.yml
         secure:
             path:     /secure
             defaults: { _controller: AppBundle:Main:secure }
             schemes:  [https]
 
     .. code-block:: xml
 
+        <!-- app/config/routing.xml -->
         <?xml version="1.0" encoding="UTF-8" ?>
 
         <routes xmlns="http://symfony.com/schema/routing"
@@ -32,6 +34,7 @@ the URI scheme via schemes:
 
     .. code-block:: php
 
+        // app/config/routing.php
         use Symfony\Component\Routing\RouteCollection;
         use Symfony\Component\Routing\Route;