[doc] Fix example to not use deprecated property

Fixes #1743

README.md

@@ -386,7 +386,7 @@ const WebSocket = require('ws');
 const wss = new WebSocket.Server({ port: 8080 });
 
 wss.on('connection', function connection(ws, req) {
-  const ip = req.connection.remoteAddress;
+  const ip = req.socket.remoteAddress;
 });
 ```