Previously, following these instructions lead to a failure with:
Error: failed to create composite formatter: failed to initialise formatter nixf-diagnose: formatter command not found in PATH: error looking up 'nixf-diagnose'
currently ./format does a bunch of stuff with git that was only necessary for nixfmt but not nixfmt-tree, so I deleted it (just use treefmt command directly instead). I also added keep sorted to keep the really long module lists sorted (already used in nixpkgs).
Having the tests available in the main Nix Flake introduces
unnecessary evaluation for non-developer users and, worse, a
dependency on the nmt library.
Fixes#6354
* PR_TEMPLATE: Note nix3 test method in checklist
Allows for running with the `nixpkgs` from the lock file, as well as
using a more familiar interface for users of the experimental CLI, which
would've avoided me opening #3971.
Also updates the corresponding note in `docs/contributing.adoc` to have
the correct invocation path.
* PR_TEMPLATE: `the experimental CLI` -> `Flakes`
This adds a section in the documentation for describing a list of
guidelines that code in Home Manager should follow.
This also updates the pull request template to reference this new
section.
