Spec: improve contextual description of EXTEND->CREATE / CREATED->EXTENDED handling and payloads
catalyst noted in #tor-dev
that 5.1.2 (EXTEND and EXTENDED) says nothing explicitly
about an OR's (relays receiving an EXTEND or EXTEND2 cell
) responsibility to send a corresponding CREATE/CREATE2 cell to the requested next node
.
catalyst, asn, nickm, and I chatted a bit about it.
I bought up that 5.3 mentions an OR's role of translating EXTEND -> CREATE and CREATED -> EXTENDED
and suggested we might reference that section from 5.1 and 5.1.2
.
It's probably enough to do that, but if some other change makes more sense (when actually putting together the wording), do that.