minor #9168 Fixed the priority of the sticky locale example (javiereguiluz)

This PR was squashed before being merged into the 2.7 branch (closes #9168).

Discussion
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Fixed the priority of the sticky locale example

This fixes #9164.

Commits
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a859e36 Fixed the priority of the sticky locale example

Author: javiereguiluz

session/locale_sticky_session.rst

@@ -54,8 +54,8 @@ how you determine the desired locale from the request::
         public static function getSubscribedEvents()
         {
             return array(
-                // must be registered after the default Locale listener
-                KernelEvents::REQUEST => array(array('onKernelRequest', 15)),
+                // must be registered before (i.e. with a higher priority than) the default Locale listener
+                KernelEvents::REQUEST => array(array('onKernelRequest', 20)),
             );
         }
     }