add usage example

README.md

@@ -6,3 +6,29 @@ two features:
 1. receive data through tcp and forward it through websocket connection
 
 2. receive data through websocket and forward it to upstream tcp port
+
+
+usage example
+=====
+
+### proxy ssh connection ###
+
+on server side, listen for websocket connection and forward it to ssh port, example config
+
+    proxy_config:
+        - listen: ws://127.0.0.1:2222/p1
+          remote: tcp://127.0.0.1:22
+
+start server side proxy by `wstunnel -c server.yaml`
+
+on client side, forward the connection through websocket, example config
+
+    proxy_config:
+        -  listen: tcp://127.0.0.1:9001
+           remote: ws://127.0.0.1:2222/p1
+
+start client side proxy by `wstunnel -c client.yaml`
+
+now, you can connect to ssh server by `ssh -p 9001 127.0.0.1`, your ssh connection hide in websocket
+
+the websocket can be proxied by nginx also