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.
- In code, add the necessary bool
- document meaning in the config file
- actually expand the full text if the entry is local and set to expanding-
by-default. This implementation is a bit lazy since it just pretends
to click on the toggle button.
- While here, reduce scope for UB by initializing POD members
