[10.x] Document assertCount method (#9244)

* Add assertCount method

* pass parameter

* Update queues.md

---------

Co-authored-by: Taylor Otwell <taylor@laravel.com>

Author: xurshudyan

queues.md

@@ -2135,6 +2135,9 @@ You may use the `Queue` facade's `fake` method to prevent queued jobs from actua
 
             // Assert that a Closure was pushed to the queue...
             Queue::assertClosurePushed();
+
+            // Assert the total number of jobs that were pushed...
+            Queue::assertCount(3);
         }
     }