[ServiceBus] update release notes
# Release History
-## 7.4.0 (Unreleased)
+## 7.4.0 (2021-11-09)
### Features Added
-- Added support to create and update queues and topics of large message size to `ServiceBusAdministrationClient`. This feature is only available for Service Bus of Premium Tier.
+- GA the support to create and update queues and topics of large message size to `ServiceBusAdministrationClient`. This feature is only available for Service Bus of Premium Tier.
- Methods`create_queue`, `create_topic`, `update_queue`, `update_topic` on `ServiceBusAdministrationClient` now take a new keyword argument `max_message_size_in_kilobytes`.
- `QueueProperties` and `TopicProperties` now have a new instance variable `max_message_size_in_kilobytes`.
- The constructor of`ServiceBusAdministrationClient` as well as `ServiceBusAdministrationClient.from_connection_string` now take keyword argument `api_version` to configure the Service Bus API version. Supported service versions are "2021-05" and "2017-04".
