Hello!
I'm a mortal so I don't know how to contribute this fix myself, so I figured this might be the right place to ask.
https://git-scm.com/docs/hash-function-transition (2.55.0) links to https://shattered.io (which used to be the SHA-1 paper), but now it's some cybersecurity editorial thing trying to ride off the SEO I assume.
web.archive.org caught the domain being parked in May 03 2026 at https://web.archive.org/web/20260503225438/https://shattered.io/
The last good snapshot seems to be at https://web.archive.org/web/20260207211148/https://shattered.io/, the link should be swapped out.
Cheers,
Mae