[FR] org-num-mode inverse defaults

[Maske]

Hi

From the first day, I liked org-num-mode, but I think that its default which numbers all headlines could be problematic.

Right now it only has the options to exclude headlines from being numbered, so it could be necessary to modify a big amount of headlines, for numbering just a tree.

I think it would be helpful to have a "positive" way to numbering headlines, for example "NUMBERED" keyword, while all the other headlines stay unnumbered.

Bests