Update datasets.rst issue with running example code (apache#35035)

dataset list is a list so running `print(dataset, dataset_list, dataset_list[dataset])` causes a `TypeError: list indices must be integers or slices, not str`

lastly that attribute name should be `dag_id` and not `dag_run_id`

docs/apache-airflow/authoring-and-scheduling/datasets.rst

@@ -230,8 +230,8 @@ Example:
         @task
         def print_triggering_dataset_events(triggering_dataset_events=None):
             for dataset, dataset_list in triggering_dataset_events.items():
-                print(dataset, dataset_list, dataset_list[dataset])
-                print(dataset_list[dataset][0].source_dag_run.dag_run_id)
+                print(dataset, dataset_list)
+                print(dataset_list[0].source_dag_run.dag_id)
 
         print_triggering_dataset_events()