doc change (#35075)

Co-authored-by: Shubham <shubhamraj@cloudera.com>

docs/apache-airflow/core-concepts/dags.rst

@@ -105,7 +105,7 @@ There are two main ways to declare individual task dependencies. The recommended
 
 Or, you can also use the more explicit ``set_upstream`` and ``set_downstream`` methods::
 
-    first_task.set_downstream(second_task, third_task)
+    first_task.set_downstream([second_task, third_task])
     third_task.set_upstream(fourth_task)
 
 There are also shortcuts to declaring more complex dependencies. If you want to make two lists of tasks depend on all parts of each other, you can't use either of the approaches above, so you need to use ``cross_downstream``::