Update README.md

Author: cloudwebrtc

README.md

@@ -9,6 +9,9 @@ Chrome/Firefox/Safari
 - Run `npm start` and open https://your_sever_ip_or_domain:8086 to use html5 demo. 
 - If you need to test mobile app, please check the [webrtc-flutter-demo](https://github.com/cloudwebrtc/flutter-webrtc-demo). 
 
+## Note
+This example can only be used for LAN testing. If you need to use it in a production environment, you need more testing and and deploy an available turn server.
+
 ## screenshots
 # iOS/Android
 <img width="180" height="320" src="https://raw.githubusercontent.com/cloudwebrtc/flutter-webrtc-server/master/screenshots/ios-01.jpeg"/> <img width="180" height="320" src="https://raw.githubusercontent.com/cloudwebrtc/flutter-webrtc-server/master/screenshots/ios-02.jpeg"/> <img width="180" height="320" src="https://raw.githubusercontent.com/cloudwebrtc/flutter-webrtc-server/master/screenshots/android-01.png"/> <img width="180" height="320" src="https://raw.githubusercontent.com/cloudwebrtc/flutter-webrtc-server/master/screenshots/android-02.png"/>