Foundations should be citable with a DOI

[brian-rose]

As I mused about over at ProjectPythia/cookbook-gallery#15, the Foundations book should be citable with a DOI pointing to specific tagged versions of the book. Zenodo makes this pretty simple.

We would need to create a tagged Release of the source repo. I think this would be a good summer goal, once we get a few of the outstanding content gaps resolved, such as #232 (work in progress in #248)

[brian-rose]

Elevating this to high priority as we want to get our DOI mechanism in place for Cookbooks prior to the summer 2023 hackathon.

This is related to creating releases #344

[jukent]

I think this is addressed by the two PRs referenced above. We should discuss if this is adequate or if you have something more specific in mind.