fix controller matching documentation and add warning

Resources/doc/reference/configuration/headers.rst

@@ -27,7 +27,7 @@ checked in the order specified, where the first match wins.
  # match all actions of a specific controller
  -
  match:
- attributes: { _controller: ^AcmeBundle:Default:.* }
+ attributes: { _controller: ^Acme\\TestBundle\\Controller\\DefaultController::.* }
  additional_cacheable_status: [400]
  headers:
  cache_control:

Resources/doc/reference/configuration/match.rst

@@ -81,8 +81,16 @@ _controller
 
 Controller name regular expression. Note that this is the controller name used
 in the route, so it depends on your route configuration whether you need
-``Bundle:Name:action`` or ``service.id:methodName`` (if you defined your
-`controllers as services`_).
+``Acme\\TestBundle\\Controller\\NameController::hello`` or ``acme_test.controller.name:helloAction``
+for `controllers as services`_.
+
+.. warning::
+
+ Symfony always expands the short notation in route definitions. Even if you
+ define your route as ``AcmeTestBundle:Name:hello`` you still need to use
+ the long form here. If you use a service however, the compiled route still
+ uses the service name and you need to match on that. If you mixed both, you
+ can do a regular expression like ``^(Acme\\TestBundle|acme_test.controller)``.
 
 _route
 ^^^^^^