[#5008] Shortening section and moving much of the note to reference

Author: weaverryan

book/http_cache.rst

@@ -168,21 +168,9 @@ from your application and returning them to the client.
 
 .. caution::
 
-    By default, a kernel based on the cache ignores the ``framework.http_method_override``
-    option, which could lead to errors when using ``PUT``, ``DELETE`` and ``PURGE``
-    methods in HTTP requests.
-
-    Invoke the ``enableHttpMethodParameterOverride()`` method before creating the
-    ``Request`` object in order to take this option into account::
-
-        // web/app.php
-
-        // ...
-        $kernel = new AppCache($kernel);
-
-        Request::enableHttpMethodParameterOverride(); // <-- add this line
-        $request = Request::createFromGlobals();
-        // ...
+    If you're using the :ref:`framework.http_method_override <configuration-framework-http_method_override>`
+    option to read the HTTP method from a ``_method`` parameter, see the
+    above link for a tweak you need to make.
 
 .. tip::
 

reference/configuration/framework.rst

@@ -82,6 +82,24 @@ method gets called automatically. It becomes the service container parameter
 named ``kernel.http_method_override``. For more information, see
 :doc:`/cookbook/routing/method_parameters`.
 
+.. caution::
+
+    If you're using the :ref:`AppCache Reverse Proxy <symfony2-reverse-proxy>`
+    with this option, the kernel will ignore the ``_method`` parameter,
+    which could lead to errors.
+
+    To fix this, invoke the ``enableHttpMethodParameterOverride()`` method
+    before creating the ``Request`` object::
+
+        // web/app.php
+
+        // ...
+        $kernel = new AppCache($kernel);
+
+        Request::enableHttpMethodParameterOverride(); // <-- add this line
+        $request = Request::createFromGlobals();
+        // ...
+
 ide
 ~~~