List null driver in list of queue drivers.

config/queue.php

@@ -11,7 +11,7 @@ return [
 	| API, giving you convenient access to each back-end using the same
 	| syntax for each one. Here you may set the default queue driver.
 	|
-	| Supported: "sync", "beanstalkd", "sqs", "iron", "redis"
+	| Supported: "null", "sync", "beanstalkd", "sqs", "iron", "redis"
 	|
 	*/