Add notice regarding library usage

This mirrors the note in .NET code snippet

Author: Doğan Erişen

articles/active-directory/develop/multi-service-web-app-access-microsoft-graph-as-user.md

@@ -275,7 +275,12 @@ public class IndexModel : PageModel
 
 # [Node.js](#tab/programming-language-nodejs)
 
-The web app gets the user's access token from the incoming requests header, which is then passed down to Microsoft Graph client to make an authenticated request to the `/me` endpoint.
+Using the [microsoft-identity-express](https://github.com/Azure-Samples/microsoft-identity-express) package, the web app gets the user's access token from the incoming requests header. microsoft-identity-express detects that the web app is hosted in App Service and gets the access token from the App Service authentication/authorization module. The access token is then passed down to the Microsoft Graph client to make an authenticated request to the `/me` endpoint.
+
+> [!NOTE]
+> The microsoft-identity-express package isn't required in your web app for basic authentication/authorization or to authenticate requests with Microsoft Graph. It's possible to [securely call downstream APIs](../../app-service/tutorial-auth-aad.md#call-api-securely-from-server-code) with only the App Service authentication/authorization module enabled.
+> 
+> However, the App Service authentication/authorization is designed for more basic authentication scenarios. Later, when your web app needs to handle more complex scenarios, you can disable the App Service authentication/authorization module and microsoft-identity-express will already be a part of your app.
 
 To see this code as part of a sample application, see *graphController.js* in the [sample on GitHub](https://github.com/Azure-Samples/ms-identity-easyauth-nodejs-storage-graphapi/tree/main/2-WebApp-graphapi-on-behalf).
 
@@ -328,4 +333,4 @@ If you're finished with this tutorial and no longer need the web app or associat
 ## Next steps
 
 > [!div class="nextstepaction"]
-> [App service accesses Microsoft Graph as the app](multi-service-web-app-access-microsoft-graph-as-app.md)
+> [App service accesses Microsoft Graph as the app](multi-service-web-app-access-microsoft-graph-as-app.md)