WebSocket example & link to MDN API reference (#19558)

Added a simple example to the WebSocket info for a frontend and backend, and a link to the Mozilla API for further learnings

guide/english/html/web-sockets/index.md

@@ -21,3 +21,34 @@ WebSockets do not need repeated calls to respond. It is enough to make one reque
 ## When not to use WebSockets?
 
 WebSockets are already supported in 95% of browsers, but sometimes this technology is not required. For example, if you are creating a simple CMS where real-time functionality is not required.
+
+## WebSocket Example
+> Frontend (No need for an import, WebSockets are supported by [every major browser])
+```javascript
+const ws = new WebSocket('ws://localhost:3000');
+
+ws.onmessage = function(e){
+    console.log('Message received from WebSocket');
+    const parsedData = JSON.parse(e.data);
+    handleData(parsedData);
+};
+
+ws.onopen = function(){
+    console.log('Websocket open');
+}
+```
+
+> Backend (uses [ws](https://github.com/websockets/ws) and [express](https://expressjs.com/), the most common WebSocket client web framework for NodeJS)
+```javascript
+const SocketServer = require('ws').Server;
+const router = require('express').Router();
+
+const server = express()
+    .use('/', router)
+    .listen(3000, () => console.log('Listening on 3000'));
+
+const wss = new SocketServer({ server });
+```
+
+## Learn more
+[Official Mozilla API](https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API)