containerize generating k8s reference documentation script

The [update-imported-docs.py](https://github.com/kubernetes/website/tree/master/update-imported-docs) that is used to generate the kubernetes documentation reference should be containerized to make it easier for users that want to update the ref docs.
This container should include all the tooling mentioned in the [quickstart](https://kubernetes.io/docs/contribute/generate-ref-docs/quickstart/).

Q: ~OS~ Linux flavor preferences for the container?
Q: Locally buildable Dockerfile or push an already created image to hub.docker.com/quay.io?
Q: Anything else worth mentioning that i've missed

cc @sftim @reylejano @jimangel @irvifa

/assign
/priority important-soon - targeting this change before 1.22 release