Update AAD DS enablement doc

Author: yuemlu

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

@@ -5,16 +5,16 @@ author: roygara
 
 ms.service: storage
 ms.topic: conceptual
-ms.date: 08/08/2019
+ms.date: 01/06/2020
 ms.author: rogarana
 ms.subservice: files
 ---
 
-# Enable Azure Active Directory Domain Services authentication over SMB for Azure Files
+# Enable Azure Active Directory Domain Services authentication on Azure Files
 
 [!INCLUDE [storage-files-aad-auth-include](../../../includes/storage-files-aad-auth-include.md)]
 
-For an overview of Azure AD authentication over SMB for Azure Files, see [Overview of Azure Active Directory authentication over SMB for Azure Files](storage-files-active-directory-overview.md).
+For an overview of the identity-based authentication supported on Azure Files, see [Overview of Azure Active Directory authentication over SMB for Azure Files](storage-files-active-directory-overview.md). This article is focused on how to enable authentication with Azure Active Directory Domain Services (Azure AD DS) on Azure Files. If you are interested in leveraging customer-managed Active Directory (AD) as the directory service for Azure Files authentication, see [Enable Customer-managed Active Directory authentication on Azure Files](../../../includes/???)
 
 [!INCLUDE [updated-for-az](../../../includes/updated-for-az.md)]
 
@@ -67,7 +67,7 @@ Before you enable Azure AD over SMB for Azure Files, make sure you have complete
 
 ## Enable Azure AD DS authentication for your account
 
-To enable Azure AD DS authentication over SMB for Azure Files, you can set a property on storage accounts created after September 24, 2018, by using the Azure portal, Azure PowerShell, or Azure CLI. Setting this property registers the storage account with the associated Azure AD DS deployment. Azure AD DS authentication over SMB is then enabled for all new and existing file shares in the storage account.
+To enable Azure AD DS authentication over SMB for Azure Files, you can set a property on storage accounts by using the Azure portal, Azure PowerShell, or Azure CLI. Setting this property implicitly "domain joins" the storage account with the associated Azure AD DS deployment. Azure AD DS authentication over SMB is then enabled for all new and existing file shares in the storage account.
 
 Keep in mind that you can enable Azure AD DS authentication over SMB only after you have successfully deployed Azure AD DS to your Azure AD tenant. For more information, see the [prerequisites](#prerequisites).