Only premium tier SB is supported for EG integration

Service Bus should be of Premium tier, for being event source in Event Grid system topic.

Author: Amitchauhangit

articles/event-grid/event-schema-service-bus.md

@@ -9,6 +9,9 @@ ms.date: 09/15/2021
 
 This article provides the properties and schema for Service Bus events. For an introduction to event schemas, see [Azure Event Grid event schema](event-schema.md).
 
+>[!NOTE]
+> Only Service Bus namespace of **Premium** tier supports event integration. **Basic** and **Standard** tiers do *not* support integration with Event Grid.
+
 [!INCLUDE [event-grid-service-bus.md](../service-bus-messaging/includes/event-grid-service-bus.md)]
 
 ## Tutorials and how-tos