Update README.md

Author: ghost1372

README.md

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 # HandyDoc
  Offline Documentions for HandyControl
+ 
+ you can download app from GitHub [Release](https://github.com/HandyOrg/HandyDoc/releases)
+![HandyDoc](https://user-images.githubusercontent.com/9213496/104024161-ec58e780-51d7-11eb-9d6a-2c6e39c5142d.png)
+![HandyDoc](https://user-images.githubusercontent.com/9213496/104024171-efec6e80-51d7-11eb-8c5e-30d2b4b269e3.png)