Document how to get the external IP of the ingress deployed using the Kubernetes page

Description

In CI/CD > Kubernetes you can install nginx-ingress to provide a public ip address to reach your applications. At the moment the address is not available in the UI, and we should document exactly how to get this information.

1. connect to the cluster (in case of GKE clusters)

gcloud container clusters get-credentials <cluster-name> --zone <zone-name> --project <project-id>

1. get the external ip address for the load balancer

kubectl get svc --namespace=gitlab-managed-apps ingress-nginx-ingress-controller -o jsonpath='{.status.loadBalancer.ingress[0].ip}'; echo

Example:

$ gcloud container clusters get-credentials test-cluster --zone us-central1-a --project test-project-123456
Fetching cluster endpoint and auth data.
kubeconfig entry generated for test-cluster.
$ kubectl get svc --namespace=gitlab-managed-apps ingress-nginx-ingress-controller -o jsonpath='{.status.loadBalancer.ingress[0].ip}'; echo
93.184.216.34