Merge pull request #1125 from samrjenkins/fix-unused-render-content-documentation

[Fix #1116] Update Rails/UnusedRenderContent documentation to recommend use of `head` instead of `render`

Author: koic

lib/rubocop/cop/rails/unused_render_content.rb

@@ -14,8 +14,8 @@ module Rails
       #   render status: 100, plain: 'Ruby!'
       #
       #   # good
-      #   render status: :continue
-      #   render status: 100
+      #   head :continue
+      #   head 100
       class UnusedRenderContent < Base
         include RangeHelp