Add DOIs to citations on RTD

[trey-stafford]

Description

Add DOIs to QGreenland citations on ReadTheDocs. https://qgreenland.readthedocs.io/en/latest/citing.html

Checklist

If an item on this list is done or not needed, check it with [x] or click the
checkbox.

• The PR description links to issues that it resolves with closes #{issue_number}
• Config lockfile updated (inv config.export > qgreenland/config/cfg-lock.json)
• Environment lockfile updated if needed (conda-lock)
• Version bumped if needed (bumpversion (major|minor|patch|prerelease|build))
• CHANGELOG.md updated (for user-facing changes)
• Documentation updated if needed
• New unit tests if needed

[mfisher87]

LGTM!

[trey-stafford]

This is the bumpversion-driven citation section. The {{ release }} bit above is a myst substitution based on the software's current version number.

I hard-coded the DOI to v3, our latest release, but a future release will mean this is wrong.

We could use the "cite all versions" doi here, but it does mean that someone that copies and uses this citation, intending to get the v3 citation, might end up with a DOI that points to e.g., v4 in a year or two from now. Maybe that's not a huge concern, since the version number would still be in the citation?

@mfisher87 , any thoughts?