fix incorrect class name [ci skip]

actionpack/lib/action_controller/metal/strong_parameters.rb

@@ -797,7 +797,7 @@ module ActionController
   #
   #   class PeopleController < ActionController::Base
   #     # Using "Person.create(params[:person])" would raise an
-  #     # ActiveModel::ForbiddenAttributes exception because it'd
+  #     # ActiveModel::ForbiddenAttributesError exception because it'd
   #     # be using mass assignment without an explicit permit step.
   #     # This is the recommended form:
   #     def create

guides/source/action_controller_overview.md

@@ -203,7 +203,7 @@ predefined raise/rescue flow to end up as a 400 Bad Request.
 
 ```ruby
 class PeopleController < ActionController::Base
-  # This will raise an ActiveModel::ForbiddenAttributes exception
+  # This will raise an ActiveModel::ForbiddenAttributesError exception
   # because it's using mass assignment without an explicit permit
   # step.
   def create