Add important plugins as one of the tasks of the release

[ci skip]

RELEASING_RAILS.rdoc

@@ -25,6 +25,18 @@ for Rails.  You can check the status of his tests here:
 
 Do not release with Red AWDwR tests.
 
+=== Are the supported plugins working? If not, make it work.
+
+Some Rails plugins are important and need to be supported until Rails 5.
+As these plugins are outside the Rails repository it is easy to break then without knowing
+after some refactoring or bug fix, so it is important to check if the following plugins
+are working with the versions that will be released:
+
+* https://github.com/rails/protected_attributes
+* https://github.com/rails/activerecord-deprecated_finders
+
+Do not release red plugins tests.
+
 === Do we have any Git dependencies?  If so, contact those authors.
 
 Having Git dependencies indicates that we depend on unreleased code.