add facade

Author: hehonghui

README.md

@@ -48,3 +48,5 @@
 | ------------- |:-------------:| ------------- |
 |    单例模式    |  [singleton](singleton/mr.simple)	 | [Mr.Simple](https://github.com/bboyfeiyu)
 |    Builder模式    |  [builder](builder/mr.simple)	 | [Mr.Simple](https://github.com/bboyfeiyu)
+|    外观模式    |  [facade](facade/elsdnwn)	 | [elsdnwn](https://github.com/elsdnwn)
+