GH-39600: [R] Add trademark attribution to pkgdown site footer

[thisisnic]

Rationale for this change

Per ASF policy, documentation pages should include trademark attribution in the footer. See #39461 for the broader effort.

What changes are included in this PR?

Add Apache trademark attribution text to the R pkgdown site footer.

Are these changes tested?

Documentation only. Can verify by building pkgdown site locally.

Are there any user-facing changes?

Footer now includes trademark text matching the main Arrow website.

---

This PR was generated by Claude. All outputs were reviewed and confirmed before pushing.

• GitHub Issue: [R] Use correct attribution in the footer of pkgdown site #39600

[thisisnic]

@github-actions crossbow submit preview-docs

[github-actions]

⚠️ GitHub issue #39600 has been automatically assigned in GitHub to PR creator.

[github-actions]

Revision: 5e14191

Submitted crossbow builds: ursacomputing/crossbow @ actions-3bc0f1949a

Task	Status
preview-docs

[thisisnic]

View preview: https://s3.amazonaws.com/arrow-data/pr_docs/49332/r/index.html

[jonkeane]

I'm not a huge huge fan of the formatting, at a minimum I wish it had a bit more whitespace between the older version bit and the legal text.

I have some suggestions for making it a separate component which might help some, but we maybe nee do <div style="...">...</div> to make this a little more separate from the current footer.

Alternatively: if it were the full length of the screen slightly above the current footer that might make it stand out a little bit less (in a good way)?

[thisisnic]

Yeah, agreed @jonkeane, let's see if that looks a bit cleaner now

[thisisnic]

@github-actions crossbow submit preview-docs

[github-actions]

Revision: 28d5197

Submitted crossbow builds: ursacomputing/crossbow @ actions-d9ecea3de6

Task	Status
preview-docs

[jonkeane]

Maybe we could warp this in <div class="pkgdown-footer-notice">...</div> and then do something like this in css:

footer {
    display: flex;
    flex-wrap: wrap;
  }

  .pkgdown-footer-left {
    flex: 1;
  }

  .pkgdown-footer-right {
    flex: 1;
    text-align: right;
  }

  .pkgdown-footer-notice {
    order: -1;          /* moves it visually above the other two */
    flex-basis: 100%;   /* forces it onto its own row */
    text-align: center;
    margin-bottom: 0.5em;
  }

?

[jonkeane]

Thanks for iterating with this.

https://s3.amazonaws.com/arrow-data/pr_docs/49332/r/ are the docs I'm looking at. They look good, though our Kapa tag is now overlaying them:

[thisisnic]

@github-actions crossbow submit preview-docs

[github-actions]

Revision: 8e3239d

Submitted crossbow builds: ursacomputing/crossbow @ actions-4f1140cf99

Task	Status
preview-docs

[thisisnic]

They look good, though our Kapa tag is now overlaying them:

I can't tell if the latest fix is any different to those ones, as the past preview is stale, but it's no worse than the status quo - are you happy if we merge either the most recent one or previous one? The Kapa tag moves when we scroll, so it doesn't always overlap it.

[jonkeane]

I honeslty forgot what the previous version looked like 😬 But yeah we can merge this or that and maybe make it nicer later?

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 3 benchmarking runs that have been run so far on merge-commit eb6108d.

There were no benchmark performance regressions. 🎉

The full Conbench report has more details. It also includes information about 1 possible false positive for unstable benchmarks that are known to sometimes produce them.