modify README

Author: itdoudoutech

doudou/README.md

@@ -15,6 +15,8 @@ Python技术 公众号文章代码库
 + [epidemic-big-screen](https://github.com/JustDoPython/python-examples/tree/master/doudou/2020-04-20-epidemic-big-screen)：疫情数据大屏
 
 + [520](https://github.com/JustDoPython/python-examples/tree/master/doudou/2020-05-17-520)：Python 教你花式表白小姐姐
+
++ [字符画](https://github.com/JustDoPython/python-examples/tree/master/doudou/2020-05-17-character-drawing)：字符画
 ---
 
 从小白到工程师的学习之路。