Update session-host-update.md

Added cross-sub issue

Author: cmckitterick

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

@@ -97,7 +97,7 @@ Here are known issues and limitations:
 
 - For session hosts that were created from an Azure Compute Gallery shared image that has a purchase plan, the plan isn't retained when the session hosts are updated. To check whether the image you use for your session hosts has a purchase plan, you can use [Azure PowerShell](/azure/virtual-machines/windows/cli-ps-findimage) or [Azure CLI](/azure/virtual-machines/linux/cli-ps-findimage).
 
-- Session host update currently requires access to the public Azure Storage endpoint `wvdhpustgr0prod.blob.core.windows.net` to deploy the RDAgent. Until this is migrated to a [required endpoint for Azure Virtual Desktop](/azure/virtual-desktop/required-fqdn-endpoint), session hosts that can't access `wvdhpustgr0prod.blob.core.windows.net` fail to be updated with the error `CustomerVmNoAccessToDeploymentPackageException`.
+- Session host configurations do not currently support accessing Gallery images that are located in a different Azure subscription than the host pool.
 
 - The size of the OS disk can't be changed during an update. The update service defaults to the same size as defined by the gallery image.