When there are multiple entries, the overall weight of the
module is divided between the entries: currently each entry
takes an equal amount of space in the overall progress.
When there are multiple entries which take wildly different
amounts of time (e.g. a squash-fs and a single file) then
the progress overall looks weird: the squash-fs gets half
of this module's weight, and the single file does too.
With the new *weight* key for entries, that division can
be tweaked so that progress looks more "even".
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.
