Justfile: add convenient wrapper around nixos-install

Justfile

@@ -285,6 +285,9 @@ run-with-channels +cmds:
 	source $(just -v _get_nix_path {{invocation_directory()}}/nix/variables/versions.nix)
 	{{cmds}}
 
+install-config config root:
+	sudo just run-with-channels nixos-install -I nixos-config={{invocation_directory()}}/{{config}} --root {{root}} --no-root-passwd
+
 # Switch between gpg-card capable devices which have a copy of the same key
 switch-gpg-card:
 	#!/usr/bin/env bash