Added composed image info for 2503 what's new

Author: alkohli

azure-local/whats-new.md

@@ -84,6 +84,8 @@ This is a baseline release with the following features and improvements:
 
 - **Azure Local VM changes**: You can now connect to an Azure Local VM using the SSH/RDP protocol without the need for line of sight (inside the host network). For more information, see [Connect to an Azure Local VM using SSH](./manage/connect-arc-vm-using-ssh.md).
 
+- **Add and repair node changes**: Starting with this release, you'll need to use the OS image of the same solution version as that running on the existing cluster. For more information on the OS image, see [Add a node](./manage/add-server.md) and [Repair a node](./manage/repair-server.md). 
+
 - **What's new for migration**: Documentation for improvements and features for VM migration to Azure Local is now available. For more information, see [What's new in migration](./migrate/migrate-whats-new.md).