Update whats-new.md

Author: sipastak

articles/virtual-desktop/whats-new.md

@@ -22,6 +22,10 @@ Make sure to check back here often to keep up with new updates.
 > [!TIP]
 > See [What's new in documentation](whats-new-documentation.md), where we highlight new and updated articles for Azure Virtual Desktop.
 
+## December 2024
+
+There were no changes to Azure Virtual Desktop in December 2024.
+
 ## November 2024
 
 Here's what changed in November 2024: