Clarify the bandwidth part of dir-spec

People keep asking about the precise meaning of relay bandwidths. We should make the spec clearer:

https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt#n424

In particular:

  • there is a separate limit on inbound and outbound traffic
  • traffic includes origin circuits and BEGINDIR requests
  • let's check if traffic includes DirPort, I think it would have to

There may also be more feedback in #25854 (moved).

I'm tagging this fast-fix, because I can fix it fast, and it will save me time when I next explain it.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information