Rename cmd -> examples

examples/mcping/README.md

@@ -0,0 +1,17 @@
+# mcping
+
+Ping tool for Minecraft: Java Edition.
+Just for example. Not recommended for daily use. Use [github.com/go-mc/mcping](github.com/go-mc/mcping) instead, which including SRV parse.
+
+适用于Minecraft: Java Edition的ping工具。
+只起示例作用，日常使用建议使用完整版[github.com/go-mc/mcping](github.com/go-mc/mcping)，包含SRV解析等功能。
+
+Install with go tools:  
+    ```go get -u github.com/Tnze/go-mc/cmd/mcping```
+    `$GOPATH/bin` should in your `$PATH`.
+
+Install with Homebrew:  
+    ```brew tap Tnze/tap && brew install mcping```
+
+Useage:  
+    ```mcping <hostname>[:port]```