Sorry about this.

> 2) The description of Co-authored-by in CONTRIBUTE seems misleading. I
> guess it should say something along the lines of "If the commit has
> authors other than the one listed in the Author: header (ie, the one
> passed to git commit --author")..." rather than "other than yourself".

Yes, please. That's exactly what caused my confusion.
CONTRIBUTE should tell us to use the regular git author, and then mention
that the header is available for when additional authors are needed. The
way it is written sounds like you must use the header if the author is not
you.