docs: improve upgrade instruction

Author: kenjis

user_guide_src/source/installation/upgrade_450.rst

@@ -215,7 +215,7 @@ This bug has been fixed and now a ``PageNotFoundException`` will be thrown and
 the filters will not be executed if the controller is not found.
 
 If you have code that depends on this bug, for example if you expect global filters
-to be executed even for non-existent pages, please add the necessary routes.
+to be executed even for non-existent pages, use the new :ref:`v450-required-filters`.
 
 Method Signature Changes
 ========================