docs: update README

README.md

@@ -11,11 +11,22 @@ npm install react-native-mqtt-server
 ## Usage
 
 ```js
-import { multiply } from 'react-native-mqtt-server';
-
-// ...
-
-const result = await multiply(3, 7);
+import { Server, SimpleMQBroker } from 'react-native-mqtt-server';
+
+// Use simple broker
+const broker = new SimpleMQBroker();
+broker.start();
+broker.on('connect', id => console.log('Client connected', id));
+broker.on('message', (topic, payload) => console.log('Message received', topic, payload));
+
+// Use as MQTT server directly
+const server = new Server();
+server.on('connection', client => {
+  client.on('data', packet => {
+    console.log('Packet received', packet);
+  });
+});
+server.listen(1883);
 ```
 
 ## Contributing