Add Zenodo badge to README

[jukent]

Adds link to the Zenodo page for the foundations book release.

Points to consider: badge link needs to be updated with new releases, still need to add prominent how to cite section.

Related to #309 and #344

[github-actions]

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[brian-rose]

@jukent nice work so far!

It looks like Zenodo has already created a persistent "latest version" DOI for this repo:
https://doi.org/10.5281/zenodo.7884571
which will always resolve to the most recent release: https://help.zenodo.org/#versioning

Does it make more sense to use that link rather than the version-specific link in the badge?

It might help to look around at other projects and see how they handle the versioning.

[jukent]

Yes I think that's right, it links to the latest DOI. I just wasn't sure yet when i made the PR.