Minor documentation formatting improvement

[user202729]

And redirect readers to the page. I think developers are most likely to want to build the documentation.

I think we should ignore the test-new failure, which is likely an oversight introduced in #39641 . As long as the corresponding test pass in test-long it should be fine.

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation and checked the documentation preview.

⌛ Dependencies

[github-actions]

Documentation preview for this PR (built with commit fcdda0b; changes) is ready! 🎉
This preview will update shortly after each push to this PR.

[user202729]

well, the rendering is actually incorrect. https://doc-pr-40587--sagemath.netlify.app/html/en/reference/documentation/sage_docbuild/builders#hunk1

I forgot the trailing _.

should be fixed now, but I figure it's probably a better idea for me to double check later just in case.

(also there's already a highlight:: bash at the start of the document, so that change is actually redundant.)