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.
- more flexible way to keep (all kinds of) files from the host
system, into the target system.
- WIP: substitutions like in shellprocess (@@ROOT@@, @@HOME@@ probably)
- WIP: creating a JSON file from global settings