Clarify managed auth setup in Azure documentation (#2064)

Updated instructions for using managed auth on Azure.

Author: natoverse

docs/get_started.md

@@ -65,11 +65,10 @@ deployment_name: <azure_model_deployment_name>
 ```
 
 #### Using Managed Auth on Azure
-To use managed auth, add an additional value to your model config and comment out or remove the api_key line:
+To use managed auth, edit the auth_type in your model config and *remove* the api_key line:
 
 ```yaml
 auth_type: azure_managed_identity # Default auth_type is is api_key
-# api_key: ${GRAPHRAG_API_KEY}
 ```
 
 You will also need to login with [az login](https://learn.microsoft.com/en-us/cli/azure/authenticate-azure-cli) and select the subscription with your endpoint.
@@ -116,4 +115,4 @@ Please refer to [Query Engine](query/overview.md) docs for detailed information
 - For more details about configuring GraphRAG, see the [configuration documentation](config/overview.md).
 - To learn more about Initialization, refer to the [Initialization documentation](config/init.md).
 - For more details about using the CLI, refer to the [CLI documentation](cli.md).
-- Check out our [visualization guide](visualization_guide.md) for a more interactive experience in debugging and exploring the knowledge graph.
+- Check out our [visualization guide](visualization_guide.md) for a more interactive experience in debugging and exploring the knowledge graph.