arrow

ARROW-18363: [Docs] Include warning when viewing old docs (redirecting to stable/dev docs) (#14839)

This PR is a complementary work to https://github.com/apache/arrow-site/pull/275.

It adds a version warning script tag to the `docs/source/_templates/layout.html` and _versionwarnings.js_ file into `docs/source/_static/`.

Authored-by: Alenka Frim <frim.alenka@gmail.com>
Signed-off-by: Joris Van den Bossche <jorisvandenbossche@gmail.com>