message: add resize cluster command
diff: @@ -198,6 +198,13 @@ Bringing up a cluster
  kubectl apply -f gpu-provision-daemonset.yaml
  ```
  +
  +5. Resizing your cluster.
  +
  + ```
  + gcloud alpha container clusters resize mugozero --size=8
  + ```
  +
  Launching selfplay workers on a cluster
  ---------------------------------------
  