This commit fixes dead URLs and updates documentation references,
improving accuracy and reliability.
Key changes:
- Fix dead URLs by using archived snapshots when they are detected as
down by tests.
- Update URLs to their new redirected locations.
Other supporting changes:
- Introduce long URLs for `archive.ph` links to retain the original
URLs within the documentation. It simplifies the maintenance by
removing the need to document the original locations along with the
short URLs.
- Improve some of the documentation to use more current sources,
replacing the outdated ones.
abec9def07