In spite of there being considerable documentation sometimes in the
config file, we go with CC0 because we don't want the notion of
'derived work' of a config file.
The example `settings.conf` is also CC0. Add some docs to
it while we're at it.
Added an initramfscfg module to handle pre-configuration for the Debian
update-initramfs, such as installing hooks (needed for luks/FDE support
on Debian-based distros).
Closes#254. (Cherry-picked from the pull request.)
