[AIRFLOW-4566] Document sla & sla_miss_callback task params (#5322)

airflow/example_dags/tutorial.py

@@ -50,6 +50,7 @@ default_args = {
     # 'on_failure_callback': some_function,
     # 'on_success_callback': some_other_function,
     # 'on_retry_callback': another_function,
+    # 'sla_miss_callback': yet_another_function,
     # 'trigger_rule': 'all_success'
 }
 

docs/concepts.rst

@@ -694,6 +694,11 @@ detailing the list of tasks that missed their SLA. The event is also recorded
 in the database and made available in the web UI under ``Browse->SLA Misses``
 where events can be analyzed and documented.
 
+SLAs can be configured for scheduled tasks by using the `sla` parameter.
+In addition to sending alerts to the addresses specified in a task's `email` parameter,
+the `sla_miss_callback` specifies an additional `Callable`
+object to be invoked when the SLA is not met.
+
 Email Configuration
 -------------------