style(sidebar): expand sponsorship banner on specific pages (backport #957)

[mergify]

Basic Info

Info	Please fill out this column
Ticket(s) this addresses	N/A
Does this PR contain AI-generated software?	No

---

Description of contribution in a few bullet points

• Added custom metadata property that allows expanding the sponsorship banner on specific pages. The banner will now be displayed by default on pages without a table of contents or when the property is set:

  ---
  expand_sponsorship_banner: true
  ---
  

• Displayed a full-size banner on the main index pages:

  • Home
  • Robots Using
  • About & Contact

  Note: The banner hides their tables of contents.
  On other main pages, the banner is expanded by default.

• Simplified logic for display conditions.

---

This is an automatic backport of pull request #957 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of e127b5d has failed:

On branch mergify/bp/jazzy/pr-957
Your branch is up to date with 'origin/jazzy'.

You are currently cherry-picking commit e127b5d.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   overrides/assets/stylesheets/sponsorship_banner.css
	modified:   overrides/main.html

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   docs/about_and_contact/index.md
	deleted by us:   docs/index.md
	deleted by us:   docs/robots_using/index.md

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[mergify]

@mergify[bot], your PR has failed to build. Please check CI outputs and resolve issues.

[SteveMacenski]

@AJedancov this is a good question - we don't need to update the main pages, but does the css and overrides get shared for updating the other pages too?

[AJedancov]

we don't need to update the main pages, but does the css and overrides get shared for updating the other pages too?

Yes, the changes from overrides are applied to every page in the docs. In this case, we only need to merge them. The main pages with metadata will be pulled from the rolling and processed as usual along with others. So they can be deleted (including about_and_contact and robots_using directories) to resolve the conflict.

[SteveMacenski]

Which should be retained, the css or the css and html?

[AJedancov]

Both css and html files