Update information on master node size on GKE/AWS (#9226)

* Update information on master node size on GKE/AWS

* clean up passive language

content/en/docs/setup/cluster-large.md

@@ -74,7 +74,11 @@ And the sizes we use on AWS are
 * 251-500 nodes: c4.4xlarge
 * more than 500 nodes: c4.8xlarge
 
-Note that these master node sizes are currently only set at cluster startup time, and are not adjusted if you later scale your cluster up or down (e.g. manually removing or adding nodes, or using a cluster autoscaler).
+{{< note >}}
+On Google Kubernetes Engine, the size of the master node adjusts automatically based on the size of your cluster. For more information, see [this blog post](https://cloudplatform.googleblog.com/2017/11/Cutting-Cluster-Management-Fees-on-Google-Kubernetes-Engine.html).
+
+On AWS, master node sizes are currently set at cluster startup time and do not change, even if you later scale your cluster up or down by manually removing or adding nodes or using a cluster autoscaler.
+{{< /note >}}
 
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