Update changelog for AppConfig release (Azure#17856)

Co-authored-by: Anton Kolesnyk <[email protected]>

Author: antkmsft

sdk/appconfig/azappconfig/CHANGELOG.md

@@ -1,16 +1,10 @@
 # Release History
 
-## 0.3.0 (Unreleased)
-
-### Features Added
+## 0.3.0 (2022-05-10)
 
 ### Breaking Changes
 * Changed argument semantics of `AddSetting`, `DeleteSetting`, `GetSetting`, `SetSetting`, and `SetReadOnly`.
 
-### Bugs Fixed
-
-### Other Changes
-
 ## 0.2.0 (2022-04-20)
 
 ### Breaking Changes