修改readme

README.md

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 18. [ATM取款聊聊『门面模式』](http://www.jianshu.com/p/c89a922a60c0)
 
+19. [后悔药，『备忘录模式』](http://www.jianshu.com/p/6d46b5d3fdee)
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 ![设计模式之禅](http://upload-images.jianshu.io/upload_images/2799767-4df489c0f630a241.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)