add rest to update fileshare

Author: cloga

articles/machine-learning/prompt-flow/media/faq/datastore-update-rest.png

@@ -271,9 +271,21 @@ If you encounter an error like "Access denied to list workspace secret", check w
 
 ### How do I use credential-less data store in prompt flow?
 
+#### Change auth type of data store to None
+
 You can follow [Identity-based data authentication](../how-to-administrate-data-authentication.md#identity-based-data-authentication) this part to make your data store credential-less. 
 
-To use credential-less data store in prompt flow, you need to grand enough permissions to user identity or managed identity to access the data store.
+You need change auth type of data store to None which stands for meid_token based auth. For blob/adls gen1/adls gen2 based data, you can make change from data store detail page, or CLI/SDK: https://github.com/Azure/azureml-examples/tree/main/cli/resources/datastore
+
+:::image type="content" source="./media/faq/datastore_auth_type.png" alt-text="Screenshot of auth type for datastore. " lightbox = "./media/faq/datastore_auth_type.png":::
+
+For fileshare based data store, you can only change auth type for rest api: [datastores-create-or-update](https://learn.microsoft.com/en-us/rest/api/azureml/datastores/create-or-update?view=rest-azureml-2023-10-01&tabs=HTTP#code-try-0). You can first use [datastores-get](https://learn.microsoft.com/en-us/rest/api/azureml/datastores/get?view=rest-azureml-2023-10-01&tabs=HTTP#code-try-0) to get the body properties of datastore, then change `"credentialsType": "None"`
+
+:::image type="content" source="./media/faq/datastore-update-rest.png" alt-text="Screenshot of rest for datastore update. " lightbox = "./media/faq/datastore-update-rest.png":::
+
+#### Grant permission to user identity or managed identity
+
+To use credential-less data store in prompt flow, you need to grant enough permissions to user identity or managed identity to access the data store.
 - If you're using user identity this default option in prompt flow, you need to make sure the user identity has following role on the storage account:
     - `Storage Blob Data Contributor` on the storage account, at least need read/write (better have delete) permission.
     - `Storage File Data Privileged Contributor` on the storage account, at least need read/write (better have delete) permission