Update regions

Author: yuemlu

articles/storage/files/storage-files-identity-auth-active-directory-enable.md

@@ -62,11 +62,7 @@ Azure Files AD authentication (preview) is available in [most public regions](ht
 
 Azure Files AD authentication is not available in:
 - West US
-- West US 2
-- East US
-- East US 2
-- West Europe
-- North Europe
+
 
 ## Workflow overview