Add change log

Author: Pan-Qi

src/Workloads/Workloads/ChangeLog.md

@@ -18,6 +18,11 @@
         - Additional information about change #1
 -->
 ## Upcoming Release
+* Introduced various new features by upgrading code generator. Please see details [here](https://github.com/Azure/azure-powershell/blob/main/documentation/Autorest-powershell-v4-new-features.md).
+* The parameters of the `New-AzWorkloadsMonitor`, `New-AzWorkloadsProviderInstance` and `Update-AzWorkloadsMonitor` cmdlet will be changed by new Managed Identity settings.
+    - Removed `-IdentityType` and `-IdentityUserAssignedIdentity` parameters.
+    - Added `-UserAssignedIdentity` parameter. The type of `UserAssignedIdentity` is simplified to a list of strings that is used to specify the user's assigned identity.
+    - Added `EnableSystemAssignedIdentity` to enable/disable system-assigned identities.
 
 ## Version 1.0.0
 * General availability for module Az.Workloads