add sponsor

Author: tiimgreen

README.md

@@ -5,6 +5,8 @@ A collection of cool hidden and not so hidden features of Git and GitHub. This c
 
 *Read this in other languages: [English](README.md), [한국어](README.ko.md), [日本語](README.ja.md), [简体中文](README.zh-cn.md), [正體中文](README.zh-tw.md).*
 
+GitHub Cheat Sheet is sponsored by [Drawpoint: create interactive maps and images for your website with no coding](https://www.drawpoint.io)
+
 ## Table of Contents
   - [GitHub](#github)
     - [Ignore Whitespace](#ignore-whitespace)