document how draft-release & post-release work together

[kelly-sovacool]

need a markdown file somewhere with these steps:

1. the dev decides cut a release, so they manually trigger the draft-release workflow.
2. draft-release updates the version, changelog, and citation files and creates a draft release under the Releases page.
3. the dev takes a look at the draft-release and makes sure everything is ok, then publishes the release.
4. publishing the release automatically triggers post-release to run -- it bumps the version & changelog to the next dev version, then opens a PR for the dev to review.
5. the dev reviews & merges the PR

also add screenshots