Docs: tag-based release

[angela-tran]

Closes #427

Referenced the release checklist from https://github.com/cal-itp/eligibility-server/blob/main/.github/ISSUE_TEMPLATE/release.yml and the Benefits documentation on Making a release.

Builds off #478

[angela-tran]

I'm not sure why this line is not rendering a button:

[Start a new Release on Github](https://github.com/cal-itp/eligibility-server/issues/new?labels=release&template=release.yml&title=Make+a+Release){ .md-button }

It uses the exact same syntax as the line in Benefits, which does render a button:

I compared their mkdocs.yml files and can't find an explanation.

[thekaveman]

@angela-tran one difference is we pin the versions of some of the mkdocs requirements in Benefits: https://github.com/cal-itp/benefits/blob/main/docs/requirements.txt

Maybe try those same version pins here?

[github-actions]

Coverage report

This PR does not seem to contain any modification to coverable code.

[angela-tran]

I figured out it was because we were missing attr_list! 😅

https://squidfunk.github.io/mkdocs-material/reference/buttons