doc: remove extra comma in cluster docs

PR-URL: #8557
Reviewed-By: Brian White <[email protected]>
Reviewed-By: Сковорода Никита Андреевич <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Evan Lucas <[email protected]>
Reviewed-By: Prince John Wesley <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>

Author: not-an-aardvark

doc/api/cluster.md

@@ -43,7 +43,7 @@ $ NODE_DEBUG=cluster node server.js
 23521,Master Worker 23528 online
 ```
 
-Please note that, on Windows, it is not yet possible to set up a named pipe
+Please note that on Windows, it is not yet possible to set up a named pipe
 server in a worker.
 
 ## How It Works