"1-RTT packet" is defined nowhere

[kazuho]

While the transport draft talks a lot about "1-RTT packets", the term is not defined. We also have a sentence that seem to imply that a long-header variant of 1-RTT packets might exist (https://quicwg.org/base-drafts/draft-ietf-quic-transport.html#section-7.1-4).

We refer to the packet less frequently as "short header packets" or "packet with a short header."

As a resolution, I think we might want to change the title of section 17.3 from "Short Header Packets" to "1-RTT Packets". Rest of the text can remain the same, as the first sentence of that section says that it is the only type of short header packet that we define.