Add signature snapshot

[arankaren]

Could you please add signature snapshot? for example cgit has this feature https://git.zx2c4.com/cgit/commit/?id=c712d5ac434b9ee8cb4e63a173a2538e1878637f

[jonashaag]

Can you explain what it is? I don’t think I have ever seen or used this feature

[arankaren]

I explain, have the feature of adding a .asc file to the snapshot from git notes refs/notes/signatures/tar.xz similar to cgit,
eg:

• https://git.zx2c4.com/cgit/snapshot/cgit-1.2.3.tar.xz
• https://git.zx2c4.com/cgit/snapshot/cgit-1.2.3.tar.asc

[jonashaag]

Aha! Sounds like a useful feature, although I haven't seen it used anywhere yet.

Happy to review a PR :)