In /etc/doas.conf, the last-matched rule will override all
previously-matched rules. Thus, make the default rule show up first (but
still allow some wiggle room for a user to `mkBefore` it), before any
user-defined rules.
`doas` is a lighter alternative to `sudo` that "provide[s] 95% of the
features of `sudo` with a fraction of the codebase" [1]. I prefer it to
`sudo`, so I figured I would add a NixOS module in order for it to be
easier to use. The module is based off of the existing `sudo` module.
[1] https://github.com/Duncaen/OpenDoas
