Various spec fixes to dir-spec, rend-spec-v3

There are a few commits fixing various things in some of the specs, ranging from implementation mismatches to wording here:

https://github.com/FiloSottile/torspec/compare/53b7dee30b1044ae401338a9ce4b6c76e1c431e1...ab22bd1dce3b62b6120300fdead958c6924fe553

The commit messages offer more rationale.

Trac:
Username: filippo