Add bootstrap script

Adds a very simple bootstrap script for setting up a new host. I'm not
exactly sure the best way to use this yet. Though I suppose it could be
run with some sort of "curl https://blahblah | bash" shenanigans. That
just seems like it would be about as much effort as just running the
nixos-rebuild command itself from a new host.

In any case though, this worked well for bootstrapping a new wixos
instance. So that was nice.

bootstrap.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+# bootstrap.sh
+# Usage: sudo ./bootstrap.sh <hostname>
+set -euo pipefail
+
+NEW_HOSTNAME="${1:?missing hostname}"
+FLAKE_URI="git+https://git.johnogle.info/johno/nixos-configs.git#${NEW_HOSTNAME}"
+
+export NIX_CONFIG="experimental-features = nix-command flakes"
+nixos-rebuild switch --flake "$FLAKE_URI"
+