Document use of upstream chart for Nginx
Current issue:
Update: because of discussion below with regard to the tcp-services and ingress name, the default will continue to be a custom sub-chart. This issue is now for documenting how to configure an existing nginx ingress controller for end-users that are bringing their own nginx ingress controller.
Original issue:
As part of our discussion around using upstream charts in https://gitlab.com/charts/helm.gitlab.io/issues/203, we have decided to move to using the upstream NGINX stable chart when we are able to.
At the moment the thing that is preventing us is our custom ingress code, but as part of https://gitlab.com/charts/helm.gitlab.io/issues/204 we will move the ingress object out of the nginx chart.
After https://gitlab.com/charts/helm.gitlab.io/issues/204 is complete, we can tackle this issue and use the upstream chart.