Create documentation on how to run builldah on runner installed with Operator on Openshift as unpriviledged, non-root

Use this buildah guide and the finding from the customer ticket #419114 to write documentation on how build images on Openshift with Runner Operator https://github.com/containers/buildah/blob/main/docs/tutorials/05-openshift-rootless-build.md

Ticket: https://gitlab.zendesk.com/agent/tickets/405407

Edited by Kate Grechishkina