fix incorrect method name in comment.

app/Jobs/Job.php

@@ -13,7 +13,7 @@ abstract class Job
     |
     | This job base class provides a central location to place any logic that
     | is shared across all of your jobs. The trait included with the class
-    | provides access to the "queueOn" and "delay" queue helper methods.
+    | provides access to the "onQueue" and "delay" queue helper methods.
     |
     */