cases: CI/CD for ML #350

Originally posted in #250 (comment)

I think that https://dvc.org/doc/use-cases/ci-cd-for-machine-learning belongs in this website (cml.dev) instead.

The question is do we want to only have one UC here? Not sure it would be worth its own section of the docs. It could also be linked directly from the home page instead (use cases like that one are not really docs anyway).

Follow-up Q: what other UCs (like that one) could we write for CML?

p.s. not sure about priority -- but consider that it's pretty easy to do this and it could help drive traffic to the site (potential tool adoption).