Add a link to documentation on how to get external ip in the Kubernetes cluster details page

In CI/CD > Kubernetes details page for a cluster, add a link to documentation (see https://gitlab.com/gitlab-org/gitlab-ce/issues/42691) on how to get external ip address for that cluster.

Link should point to https://docs.gitlab.com/ee/user/project/clusters/#getting-the-external-ip-address.

Proposal

Add copy to the Applications > Ingres section

After installing Ingress, you will need to point a wildcard DNS at the generated external IP address in order to view your app after it is deployed. More information