add chrome websocket compress explanation

echo/ws-echo/change_log.md

@@ -16,3 +16,4 @@
     > 2 add server/app/config.go:GettySessionParam{CompressEncoding} to test compress websocket compression extension.
 	>
 	> 3 Pls attention that ie does not support weboscket compression extension while the latest chrome support it while echo/ws-echo/server enable websocket compress function. I have not test firefox and edge.
+	>   As of version 19, Chrome will apparently compress WebSocket traffic automatically when the server supports it.