[Docs] Include warning when viewing old docs (redirecting to stable/dev docs)

[asfimport]

Now we have versioned docs, we also have the old versions of the developers docs (eg https://arrow.apache.org/docs/9.0/developers/guide/communication.html). Those might be outdated (eg regarding communication channels, build instructions, etc), and typically when contributing / developing with the latest arrow, one should always check the latest dev version of the contributing docs.

We could add a warning box pointing this out and linking to the dev docs.

For example similarly how some projects warn about viewing old docs in general and point to the stable docs (eg https://mne.tools/1.1/index.html or https://scikit-learn.org/1.0/user_guide.html). In this case we could have a custom box when at a page in /developers to point to the dev docs instead of stable docs

Reporter: Joris Van den Bossche / @jorisvandenbossche
Assignee: Alenka Frim / @AlenkaF

Related issues:

• [Docs][R] Include warning when viewing old docs (redirecting to stable docs) (is cloned by)

PRs and other links:

• GitHub Pull Request #14687
• GitHub Pull Request #14839

_{Note: This issue was originally created as ARROW-18363. Please see the migration documentation for further details.}

[asfimport]

Joris Van den Bossche / @jorisvandenbossche:
Renamed the issue to not be specific about the contributing docs, since we can also do this for all docs. I think it would only still be nice if we can special case pages in the /developers section, so that for those pages we can 1) point to the dev docs instead of stable docs, and 2) also show this warning for the stable version.

[asfimport]

Joris Van den Bossche / @jorisvandenbossche:
For example the MNE docs mentioned above do this with a piece of javascript: https://github.com/mne-tools/mne-tools.github.io/blob/main/versionwarning.js

[asfimport]

Joris Van den Bossche / @jorisvandenbossche:
There is also some work to include this upstream in the sphinx theme: pydata/pydata-sphinx-theme#780

[asfimport]

Joris Van den Bossche / @jorisvandenbossche:
Issue resolved by pull request 14839
#14839