Added limitation from regression

Author: brittanyrowe

articles/virtual-machine-scale-sets/virtual-machine-scale-sets-attach-detach-vm.md

@@ -182,6 +182,7 @@ Update-AzVM -ResourceGroupName $resourceGroupName -VM $vm -VirtualMachin
 - The scale set must use Flexible orchestration mode.
 - The scale set must have a `platformFaultDomainCount` of **1**.
 - VMs created by the scale set must be `Stopped` prior to being detached.
+- Detach of VMs created by the scale set is currently not supported in West Central US, East Asia, UK South, and North Europe.
 
 ## Moving VMs between scale sets (Preview)