Update README.md

Author: Neutree

README.md

@@ -14,6 +14,8 @@ void main()
 ```
 
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+# Chat On Gitter
+[![Gitter](https://badges.gitter.im/Neutree/STM32f103DriverLib.svg)](https://gitter.im/STM32f103DriverLib/Lobby)
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 # 如何使用