Prep for release (Azure#48393)

* Prep for release

* update changelog

* add braking changes

* file name casing changes

* add

Author: JoshLove-msft

sdk/eventgrid/Azure.Messaging.EventGrid.SystemEvents/CHANGELOG.md

@@ -1,16 +1,17 @@
 # Release History
 
-## 1.0.0-beta.2 (Unreleased)
+## 1.0.0-beta.2 (2025-02-21)
 
 ### Features Added
 
 - Exposed `JsonModelWriteCore` for model serialization procedure.
+- Added various new system events and properties for existing events.
 
 ### Breaking Changes
 
-### Bugs Fixed
-
-### Other Changes
+- MQTT event naming was fixed to use correct casing.
+- Media services events were removed as the service has been deprecated.
+- Various properties were changed to be nullable.
 
 ## 1.0.0-beta.1 (2024-06-19)