docs(content): fix e2e socket.io-redis tests for multiple app instances

Fixes multiple app instances in e2e tests not connecting properly to
socket.io-redis by reinitialising redisIOAdapter on createIOServer.

Author: vck3000

content/websockets/adapter.md

@@ -39,11 +39,11 @@ Once the package is installed, we can create a `RedisIoAdapter` class.
 import { IoAdapter } from '@nestjs/platform-socket.io';
 import redisIoAdapter from 'socket.io-redis';
 
-const redisAdapter = redisIoAdapter({ host: 'localhost', port: 6379 });
-
 export class RedisIoAdapter extends IoAdapter {
   createIOServer(port: number, options?: any): any {
     const server = super.createIOServer(port, options);
+    const redisAdapter = redisIoAdapter({ host: 'localhost', port: 6379 });
+    
     server.adapter(redisAdapter);
     return server;
   }