Kubernetes > Adding EKS Cluster > Ensure prereqs are documented

We currently list some necessary steps needed to add an AWS EKS cluster to gitlab here: https://docs.gitlab.com/ee/user/project/clusters/eks_and_gitlab/

We state the following prereqs:

1. An account on GitLab, like GitLab.com.
2. An Amazon EKS cluster (with worker nodes properly configured).
3. kubectl installed and configured for access to the EKS cluster.

These capture a very high level of the prereqs needed. It would be helpful to include all prereqs here. We should also link to this page from https://docs.gitlab.com/ee/user/project/clusters/#add-existing-kubernetes-cluster so it is easy to find.