us gov for cmk transition caveat

Author: b-ahibbard

articles/azure-netapp-files/configure-customer-managed-keys.md

@@ -79,14 +79,16 @@ Azure NetApp Files customer-managed keys is supported for the following regions:
 * UAE North
 * UK South
 * UK West
-* US Gov Arizona
-* US Gov Texas
-* US Gov Virginia
+* US Gov Arizona*
+* US Gov Texas*
+* US Gov Virginia*
 * West Europe
 * West US
 * West US 2
 * West US 3
 
+\* The ability to transition existing volumes to customer-managed keys isn't currently supported for US Gov regions. 
+
 ## Requirements
 
 Before creating your first customer-managed key volume, you must set up:
@@ -367,6 +369,9 @@ Azure NetApp Files supports the ability to move existing volumes using platform-
 
 Encryption key transition for Azure NetApp Files is currently in preview. Before using this feature for the first time, you need to register it. 
 
+>[NOTE]
+>Transitioning volumes to customer-managed keys isn't currently supported for US Gov regions. 
+
 1. Register the feature: 
 
     ```azurepowershell-interactive