Merge pull request #77 from koic/remove_obsolete_doc_for_rails_action_filter

Remove outdated doc for `Rails/ActionFilter`

Author: koic

lib/rubocop/cop/rails/action_filter.rb

@@ -8,9 +8,6 @@ module Rails
       # The cop is configurable and can enforce the use of the older
       # something_filter methods or the newer something_action methods.
       #
-      # If the TargetRailsVersion is set to less than 4.0, the cop will enforce
-      # the use of filter methods.
-      #
       # @example EnforcedStyle: action (default)
       #   # bad
       #   after_filter :do_stuff

manual/cops_rails.md

@@ -11,9 +11,6 @@ This cop enforces the consistent use of action filter methods.
 The cop is configurable and can enforce the use of the older
 something_filter methods or the newer something_action methods.
 
-If the TargetRailsVersion is set to less than 4.0, the cop will enforce
-the use of filter methods.
-
 ### Examples
 
 #### EnforcedStyle: action (default)