Add a note regarding scaling values when using auto-discovery

As per information I found here kubernetes#1013 (comment)

cluster-autoscaler/cloudprovider/aws/README.md

@@ -78,6 +78,7 @@ Note that:
 
 * It is recommended to use a second tag like `k8s.io/cluster-autoscaler/<YOUR CLUSTER NAME>` when `k8s.io/cluster-autoscaler/enabled` is used across many clusters to prevent ASGs from different clusters recognized as the node groups
 * There are no `--nodes` flags passed to cluster-autoscaler because the node groups are automatically discovered by tags
+* No min/max values are provided when using Auto-Discovery, cluster-autoscaler will respect the current min and max values of the ASG being targeted, and it will adjust only the "desired" value.
 
 ```
 kubectl apply -f examples/cluster-autoscaler-autodiscover.yaml