fix(docs): add processor in the worker

docs/gitbook/guide/connections.md

@@ -43,8 +43,12 @@ import IORedis from 'ioredis';
 const connection = new IORedis({ maxRetriesPerRequest: null });
 
 // Reuse the ioredis instance in 2 different consumers
-const myFirstWorker = new Worker('myFirstWorker', { connection });
-const mySecondWorker = new Worker('mySecondWorker', { connection });
+const myFirstWorker = new Worker('myFirstWorker', async job => {}, {
+  connection,
+});
+const mySecondWorker = new Worker('mySecondWorker', async job => {}, {
+  connection,
+});
 ```
 
 Note that in the third example, even though the ioredis instance is being reused, the worker will create a duplicated connection that it needs internally to make blocking connections. Consult the [ioredis](https://github.com/luin/ioredis/blob/master/API.md) documentation to learn how to properly create an instance of `IORedis`.