Versioned Nix/Nixpkgs/NixOS manuals

[ShamrockLee]

Describe the glitch

The "versioning" of the current URL API for the manuals are merely stable and unstable. For example,

https://nixos.org/manual/nixpkgs/stable/
https://nixos.org/manual/nixpkgs/unstable/

All the link to the Nixpkgs manual inside the (NixOS) Release Notes refers to the unstable version, making it irrelevant after release branch-off, contradicting the purpose of a release note.

This long-lasting issue can be solved by introducing versioned API to access the manual. Namely,

https://nixos.org/manual/nixpkgs/23.11/
https://nixos.org/manual/nixpkgs/24.05/

For Nix, which seems to conforms the Semantic Versioning, a gross version could be redirected to the relevant fine version. For example,

https://nixos.org/manual/nix/2.19/

could be redirected to

https://nixos.org/manual/nix/2.19.2/

Screenshots

The above screenshot contains the versioned URL typed to the browser address bar:

https://nixos.org/manual/nixos/23.11/

but the web page shows:

# Not Found
 The requested content at `/manual/nixos/23.11/` could not be found. 

Additional context
Previous discussion: NixOS/nixpkgs#234651 (review)

[garbas]

\cc @fricklerhandwerk

[fricklerhandwerk]

There is work going on here: NixOS/nix.dev#764

I also have a draft to port the Nixpkgs and NixOS manuals, but that is more work because it's being processed with a new stylesheet and wrapped with the Perl templating engine used for nixos.org (which only builds on Linux).