Update session-host-update.md

Added public access key vault as known issue

Author: cmckitterick

articles/virtual-desktop/session-host-update.md

@@ -93,7 +93,7 @@ With only a reduced number of session hosts available, you should schedule an up
 
 Here are known issues and limitations:
 
-- The current session host configuration version isn't displayed in the session host blade in the portal. Until this issue is fixed, you can access the portal using [this portal URL](https://portal.azure.com/?feature.hostpoolVirtualMachinesBladeV3=false#home) to view the current configuration version.
+- Session host update only supports key vaults that are configured to [allow public access from all networks](/azure/key-vault/general/how-to-azure-key-vault-network-security).
 
 - Session host update is only available in the global Azure cloud. It isn't available in other clouds, such as Azure US Government or Azure operated by 21Vianet.