Update README.md

env.example added hence addying copy command will be necessary

examples/websocket-server/README.md

@@ -8,6 +8,7 @@ This is an example that shows how to use `WebsocketServerTransport` to communica
 python3 -m venv venv
 source venv/bin/activate
 pip install -r requirements.txt
+cp env.example .env # and add your credentials
 ```
 
 ## Run the bot