fix typo

Author: dbu

bundles/routing/configuration.rst

@@ -476,7 +476,7 @@ The name of the Doctrine Manager to use.
 
 The route class to use in your application.
 
-versionadded:: 2.0
+.. versionadded:: 2.0
     The ``route_class`` parameter has been added in version 2.0.
 
 ``uri_filter_regexp``