nixpkgs/nixos/doc/manual/installation/installation.md

Installation

This section describes how to obtain, install, and configure NixOS for first-time use.

obtaining.chapter.md
installing.chapter.md
changing-config.chapter.md
upgrading.chapter.md
building-nixos.chapter.md
building-images-via-nixos-rebuild-build-image.chapter.md
building-images-via-systemd-repart.chapter.md