Fix usage example of queue.enqueue() (#1082)

* Fix usage example of queue.enqueue()

* Refactor enqueue example

docs/docs/index.md

@@ -83,7 +83,7 @@ to your job and not to RQ's enqueue function, this is what you do:
 
 ```python
 q = Queue('low', connection=redis_conn)
-q.enqueue(func=count_words_at_url,
+q.enqueue(count_words_at_url,
           ttl=30,  # This ttl will be used by RQ
           args=('http://nvie.com',),
           kwargs={