Document Nix installation in one place

[fricklerhandwerk]

Problem description

Currently there are five (!) sources of truth for installing Nix:

0. Nix manual (quickstart) (source)
1. Nix manual (install) (source)
2. Nix manual (binary installation) (source)
3. nixos.org (source)
4. nix.dev (source)

This creates additional maintenance overhead and leads to inconsistencies.

Proposal

Define one place where to maintain that information and either link to or reproduce it in the other locations.

[JeremiahSecrist]

I remember reading someone wanting to change the recommended installer to the one built my determinate systems located here. Do keep in mind I heard this in a fleeting manner and have no location at present online where this is pinned down.

[fricklerhandwerk]

@arouzing that is for the Nix maintainer team to decide, and we will do that eventually. This issue is purely for determining a single source of truth for the installation instructions, regardless of particular contents.

[nixos-discourse]

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

https://discourse.nixos.org/t/2023-04-13-documentation-team-meeting-notes-41/27264/1

[nixos-discourse]

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

https://discourse.nixos.org/t/install-doc-assumes-bash/53750/4