Typo on HA page

[jollofking]

As can be seen in this diagram, we will create three EC2 instances to form the cluster and a further one student-node from which to perform the configuration.

This should say five instances

https://github.com/kodekloudhub/certified-kubernetes-administrator-course/blob/master/kubeadm-clusters/aws-ha/docs/02-compute-resources.md