also dismiss implementing ordered list bullet overrides for now, e.g.
1. [@10] foo
add it once someone needs it - for now it seems like needless complexity
see https://orgmode.org/manual/Checkboxes.html
We're deviating from Org mode regarding the assigned css classes but the chosen
classes feel better than (on, off, trans) and it's not like the export matches
1:1 otherwise.