Design & Configuration of External Multiarch CI/CD K8s clusters

[cfilleke]

Is your feature request related to a problem? Please describe:
The problem is this: while preparing PRs for the s390x port of kubevirt and kubevirt CDI, there needs to be a CI/CD running on an s390x K8s cluster, available to github automation. There is currently a provisional K8s cluster provisioned in the IBM cloud for this provisioned for kubevirt build and test and there will soon be a secure permanent platform provided.

Describe the solution you'd like:
On behalf of ongoing efforts to multi-arch kubevirt and CDI which need this configured and documented, it is proposed that we have some official documentation for these external CI/CD build and test automation systems.

Describe alternatives you've considered:
The alternative is to not document these systems? Seems wrong.

Additional context:
Add any other context or screenshots about the feature request here.