Add ci to generate examples in rhcos branch

[jmarrero]

Does initial generation of the rhcos branch by changing the FROM lines on any Dockerfiles found.

For this to work I think we need:

• create rhcos branch based on the current main branch on this repository.
• to add the https://github.com/coreosbot-releng token to the secrets in this repository.
• fork this repository to github.com/coreosbot-releng/coreos-layering-examples

At least based on my tests with my forks that should make it work. But I don't have the credentials or access to do these things I believe.

[cgwalters]

Looks generally good to me, one nit.

[bgilbert]

LGTM

[bgilbert]

There's an existing rhcos branch here, and I'm not sure of its status, so I'll let other folks in this repo handle that part. I've done the other two setup steps, and I agree that the three steps together should be sufficient. 👍

[cgwalters]

There's an existing rhcos branch here, and I'm not sure of its status, so I'll let other folks in this repo handle that part.

I've pushed a copy of the current tip of rhcos as rhcos-orig for historical reference.

[jmarrero]

thank you both!