Update cluster-autoscaler.md

This link will be helpful to understand how it works

Author: jacobbaek

articles/aks/cluster-autoscaler.md

@@ -19,7 +19,7 @@ This article requires Azure CLI version 2.0.76 or later. Run `az --version` to f
 
 To adjust to changing application demands, such as between workdays and evenings or weekends, clusters often need a way to automatically scale. AKS clusters can scale in one of two ways:
 
-* The **cluster autoscaler** watches for pods that can't be scheduled on nodes because of resource constraints. The cluster then automatically increases the number of nodes.
+* The **cluster autoscaler** watches for pods that can't be scheduled on nodes because of resource constraints. The cluster then automatically increases the number of nodes. For more information, see [How does scale-up work?](https://github.com/kubernetes/autoscaler/blob/master/cluster-autoscaler/FAQ.md#how-does-scale-up-work)
 * The **horizontal pod autoscaler** uses the Metrics Server in a Kubernetes cluster to monitor the resource demand of pods. If an application needs more resources, the number of pods is automatically increased to meet the demand.
 
 ![The cluster autoscaler and horizontal pod autoscaler often work together to support the required application demands](media/autoscaler/cluster-autoscaler.png)