add scale.yml to do minimum needed for a node bootstrap

docs/getting-started.md

@@ -55,3 +55,15 @@ ansible-playbook -i my_inventory/inventory.cfg cluster.yml -b -v \
 ```
 
 See more details in the [ansible guide](ansible.md).
+
+Adding nodes
+--------------------------
+
+You may want to add worker nodes to your existing cluster. This can be done by re-running the `cluster.yml` playbook, or you can target the bare minimum needed to get kubelet installed on the worker and talking to your masters. This is especially helpful when doing something like autoscaling your clusters.
+
+- Add the new worker node to your inventory under kube-node (or utilize a [dynamic inventory](https://docs.ansible.com/ansible/intro_dynamic_inventory.html)).
+- Run the ansible-playbook command, substituting `scale.yml` for `cluster.yml`:
+```
+ansible-playbook -i my_inventory/inventory.cfg scale.yml -b -v \
+  --private-key=~/.ssh/private_key
+```