Merge pull request #21554 from ronakjangir47/added_nodoc

Added nodoc tag for the methods which returns object of private apis

activerecord/lib/active_record/associations/collection_proxy.rb

@@ -881,7 +881,7 @@ module ActiveRecord
         !!@association.include?(record)
       end
 
-      def arel
+      def arel #:nodoc:
         scope.arel
       end