docs(websockets): update adapter.md

Author: Tony133

content/websockets/adapter.md

@@ -37,21 +37,25 @@ Once the package is installed, we can create a `RedisIoAdapter` class.
 
 ```typescript
 import { IoAdapter } from '@nestjs/platform-socket.io';
-import { Server, ServerOptions } from 'socket.io';
+import { ServerOptions } from 'socket.io';
 import { createAdapter } from '@socket.io/redis-adapter';
 import { createClient } from 'redis';
 
-const io = new Server();
-const pubClient = createClient({ url: `redis://localhost:6379` });
-const subClient = pubClient.duplicate();
+export class RedisIoAdapter extends IoAdapter {
+  private adapterConstructor: ReturnType<typeof createAdapter>;
 
-pubClient.connect();
-subClient.connect();
+  async connectToRedis(): Promise<void> {
+    const pubClient = createClient({ url: `redis://localhost:6379` });
+    const subClient = pubClient.duplicate();
+
+    await Promise.all([pubClient.connect(), subClient.connect()]);
+
+    this.adapterConstructor = createAdapter(pubClient, subClient);
+  }
 
-export class RedisIoAdapter extends IoAdapter {
   createIOServer(port: number, options?: ServerOptions): any {
     const server = super.createIOServer(port, options);
-    server.adapter(createAdapter(pubClient, subClient));
+    server.adapter(this.adapterConstructor);
     return server;
   }
 }
@@ -61,7 +65,11 @@ Afterward, simply switch to your newly created Redis adapter.
 
 ```typescript
 const app = await NestFactory.create(AppModule);
-app.useWebSocketAdapter(new RedisIoAdapter(app));
+const redisIoAdapter = new RedisIoAdapter(app);
+await redisIoAdapter.connectToRedis();
+
+app.useWebSocketAdapter(redisIoAdapter);
+
 ```
 
 #### Ws library