Add comment documentation for Parameters#use

Author: dabrorius

lib/grape/dsl/parameters.rb

@@ -5,6 +5,27 @@ module DSL
     module Parameters
       extend ActiveSupport::Concern
 
+      # Include reusable params rules among current.
+      # You can define reusable params with helpers method.
+      #
+      # @example
+      #
+      #     class API < Grape::API
+      #       helpers do
+      #         params :pagination do
+      #           optional :page, type: Integer
+      #           optional :per_page, type: Integer
+      #         end
+      #       end
+      #
+      #       desc "Get collection"
+      #       params do
+      #         use :pagination
+      #       end
+      #       get do
+      #         Collection.page(params[:page]).per(params[:per_page])
+      #       end
+      #     end
       def use(*names)
         named_params = Grape::DSL::Configuration.stacked_hash_to_hash(@api.namespace_stackable(:named_params)) || {}
         options = names.last.is_a?(Hash) ? names.pop : {}