Please add cbtnummodes to dir-spec.txt
As of today, moria1 and ides set consensus parameter 'cbtnummodes' which is not described in dir-spec.txt, but only in path-spec.txt. My understanding of dir-spec.txt is that everything written in directory documents must be described in that document. We should at least mention the valid consensus parameters in dir-spec.txt and add a link to path-spec.txt.