Describe update and release-upgrade workflows separately so users can tell when to update the current branch versus move to a new Home Manager release branch.
Expand routine update instructions for flake users by explaining that flake inputs are pinned in flake.lock, showing all-input and selected-input update commands, and separating the rebuild command for standalone, NixOS module, and nix-darwin module installations.
Keep channel instructions available for standalone and system-module users, including the different channel owner used by NixOS module setups. Also correct nix-darwin terminology in the installation and flakes docs so those sections do not use NixOS-specific wording.
- Add comprehensive documentation for upgrading Home Manager channels.
- Cover channel-based, flake-based, and NixOS module methods.
- Include troubleshooting section and state version updates.
- Update examples for NixOS 25.05 compatibility.
