Move nix-serve guide from Nix manual to nix.dev

[fricklerhandwerk]

Move the contents of Serving a Nix store via HTTP to a stand-alone guide on nix.dev.

Up-to-date documentation on nix-serve: https://github.com/edolstra/nix-serve

Important
add a redirect on nixos.org, otherwise existing links will break

Context

This is to be able to implement NixOS/nix#7769 without loss.

It's not clear how important this use case is, but for the sake of completeness we should find a new home for this guide and later decide if it's still supposed to be a supported use case.

[zmitchell]

@wamirez would you like to take a crack at this?

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/2023-07-06-documentation-team-meeting-notes-61/30087/1

[siddarth2810]

Hii @fricklerhandwerk, i can take this up. So do you just want the contents of serving a nix store via HTTP to be included as a separate section in the documentation, but not under any specific categories like tutorials or guides? Or, as mentioned in the issue title, would you prefer that we create a dedicated section specifically for "nix-serve"?

[fricklerhandwerk]

Oh, that cache tutorial is supposed to be the replacement for the nix-serve guide. I suggest placing a redirect in the Nix manual and removing the page there.