Add "who builds Nix and NixOS?" to FAQ

Observations

It's not clear to newcomers that "NixOS" is both an OS and an organization, and that "NixOS" also manages "Nix".

I'm new to Nix, and I found it very confusing. I skimmed through the docs, but it only left me more confused when the "How to get help" section in the nix.dev documentation linked me to the NixOS forums.

• https://discourse.nixos.org/t/what-is-the-relationship-between-nix-and-nixos/57828

Problem

I think the "normal" assumption for newcomers is that nix was created and then some other project was created (by other people) that included nix as their package manager in a new distro called NixOS.

I think it's very confusing why the FAQ tells users to go to the NixOS forums to ask questions about nix.

The FAQ doesn't indicate the relationship between nix, NixOS, or all the other nix-related software projects in this ecosystem.

Approaches

I think we should add questions to the FAQ that address this. For example:

1. What is the relationship between nix and NixOS?
2. What other projects are managed by NixOS?
3. What other, similar projects that are not managed by NixOS?

To make this clear, I think any TLD domains that are paid for by NixOS should be clearly enumerated, so new users know what's official and what's not.

Willing to help?

Yes. If a PR is welcome, let me know and I'll submit one.

Priorities

Add 👍 to issues you find important.

Start with the nix.dev FAQ and its “How to get help” section, then read the linked Discourse discussion about the relationship between Nix and NixOS. Done means the FAQ clearly explains NixOS, Nix, related projects, and which projects or domains are official.