Fix doc in Object#respond_to_missing? (#2239)

object.c

@@ -4160,7 +4160,7 @@ rb_obj_dig(int argc, VALUE *argv, VALUE obj, VALUE notfound)
  *      DELEGATE = [:puts, :p]
  *
  *      def method_missing(name, *args, &block)
- *        super unless DELEGATE.include? name
+ *        return super unless DELEGATE.include? name
  *        ::Kernel.send(name, *args, &block)
  *      end
  *