Update dependencies and the README

sync-todo/v2/client/flutter/README.md

@@ -11,6 +11,7 @@ For this template app to work, you must ensure that `/assets/config/atlasConfig.
 
 - **appId:** your Atlas App Services App ID.
 - **baseUrl:** the App Services backend URL. This should be https://realm.mongodb.com in most cases.
+- **atlasExplorerLink:** the App Services Data Explorer URL. This should be similar to https://cloud.mongodb.com/links/<YOUR-ATLAS-PROJECT-ID>/explorer/<YOUR-CLUSTER-NAME>/database/collection/find
 
 ### Using the Atlas App Services UI
 
@@ -19,26 +20,58 @@ The easiest way to use this template app is to log on to [Atlas App Services](ht
 created, you can download this Flutter template app pre-configured for your new
 app.
 
+When you download the Flutter template from the Atlas App Services UI,
+the `atlasConfig.json` comes pre-populated with the correct values for your
+application. You can proceed to **Getting Started** below.
+
 ### Cloning from GitHub
 
 If you have cloned this repository from the GitHub
 [mongodb/template-app-dart-flutter-todo](https://github.com/mongodb/template-app-dart-flutter-todo.git)
-repository, you must create a separate App Services App with Device Sync
-enabled to use this client. You can find information about how to do this
-in the Atlas App Services documentation page:
+repository, you must create an App Services App with Device Sync
+enabled to use this client. Then, you must manually populate the values in
+the `/assets/config/atlasConfig.json` file that the Flutter client references
+when it runs.
+
+#### Create an App Services app
+
+You can find information about how to create an App Services App configured
+to run this client as a Real-Time Sync demo in the Atlas App Services
+documentation page:
 [Template Apps -> Create a Template App](https://www.mongodb.com/docs/atlas/app-services/reference/template-apps/)
 
-Once you have created the App Services App, replace any value in this client's
+#### Populate fields in your atlasConfig.json
+
+For this template app to work, you must ensure that
+`/assets/config/atlasConfig.json` exists and contains the following properties:
+
+- **appId:** your Atlas App Services App ID.
+- **baseUrl:** the App Services backend URL. This should be https://realm.mongodb.com in most cases.
+- **atlasExplorerLink:** the App Services Data Explorer URL. This should be similar to https://cloud.mongodb.com/links/<YOUR-ATLAS-PROJECT-ID>/explorer/<YOUR-CLUSTER-NAME>/database/collection/find
+
+Once you have created the App Services App, replace any value in the
 `appId` field with your App Services App ID. For help finding this ID, refer
 to: [Find Your Project or App Id](https://www.mongodb.com/docs/atlas/app-services/reference/find-your-project-or-app-id/)
 
-### Download the Client as a Zip File
+If you do not populate the `appId` field, the app will compile and run but you
+won't be able to create users or log in to Atlas.
+
+Replace any value in the `dataExplorerLink` field with your Atlas
+Data Explorer link. This link is similar to:
+
+```
+https://cloud.mongodb.com/links/YOUR-ATLAS-PROJECT-ID/explorer/YOUR-CLUSTER-NAME/database/collection/find
+```
+
+Replace `YOUR-ATLAS-PROJECT-ID` with your Atlas Project ID. For help finding
+this ID, refer to: [Find your Atlas Project Id](https://www.mongodb.com/docs/atlas/app-services/apps/metadata/#find-your-atlas-project-id)
+
+Replace `YOUR-CLUSTER-NAME` with the name of your Atlas cluster. If you accept
+the default value when you create the cluster, the cluster name is `Cluster0`.
 
-If you have downloaded this client as a .zip file from the Atlas App Services
-UI, it does not contain the App Services App ID. You must replace any value
-in this client's `appId` field in `/assets/config/atlasConfig.json`
-with your App Services App ID. For help finding this ID, refer to:
-[Find Your Project or App Id](https://www.mongodb.com/docs/atlas/app-services/reference/find-your-project-or-app-id/)
+If you do not populate the `dataExplorerLink` field, the app will compile and
+run but you will get an unhandled exception if you tap the link that says
+"To see your changes in Atlas, tap here."
 
 ## Getting Started