[ACR] Add note that only one approach needed

Author: iainfoulds

articles/container-registry/container-registry-auth-aks.md

@@ -14,7 +14,9 @@ ms.author: danlep
 
 When you're using Azure Container Registry (ACR) with Azure Kubernetes Service (AKS), an authentication mechanism needs to be established. This article details the recommended configurations for authentication between these two Azure services.
 
-This article assumes that you've already created an AKS cluster and you are able to access the cluster with the `kubectl` command-line client. 
+You only need to configure one of these authentication methods. The most common approach is to [grant access using the AKS service principal](#grant-aks-access-to-acr). If you have specific needs, you can optionally [grant access using Kubernetes secrets](#access-with-kubernetes-secret).
+
+This article assumes that you've already created an AKS cluster and you are able to access the cluster with the `kubectl` command-line client.
 
 ## Grant AKS access to ACR