Documentation on buiding docs is outdated

[AlexHls]

Describe the bug

The documentation https://tardis-sn.github.io/tardis/contributing/development/documentation_guidelines.html#sharing-the-built-documentation-in-your-pr-documentation-preview says a commit with
git commit --allow-empty -m "[build docs]"
will build the docs. The workflow file requires build-docs in the commit message.
Furthermore, the documentation does not build either way

To Reproduce

See PR #2088

Screenshots

System

• OS:

  • GNU/Linux
  • macOS

• Environment (conda list):

Additional context

[epassaro]

I would remove the documentation build section since the pull request template says clearly what you need to do in order to build the docs (just apply the build-docs label).

[isaacgsmith]

I strongly disagree since we still need to document where to access the built documentation, how to view build logs, and how to build docs online if the branch isn't part of an open PR.