Who manages Authors.txt?

Who manages Authors.txt?

Just being nosy, how is that authors.txt kept up-to-date?

There is a grunt-task for this "grunt authors", but it shows a much longer list. (arround 200 lines from the task and roughly 130 in the file)
Furthermore it seems that some updates are done manually and others occur along with some closed pull-request.

Is there some secret rule? e.g. "only users with a public email address in their profile".
Just one sample: Sai Wong (committed lots of code on October 16th) is not in the authors list.

Searching for enlightment! :-)

Cheers, Don