Most of the text has been shuffled into the swagger definitions to bring it closer to where it matters.
This also attempts to clarify what is out in the wild. Most importantly, the first version of the key exchange is outright removed from the specification. Other research points/questions are:
* What is a "Key ID"?
* 1241156c82/synapse/rest/key/v2/local_key_resource.py (L81-L83)
* 1241156c82/synapse/rest/key/v2/local_key_resource.py (L88-L91)
* Returning a cached response if the server throws a 400, 500, or otherwise not-offline status code
* 1241156c82/synapse/rest/key/v2/remote_key_resource.py (L227-L229)
* `minimum_valid_until_ts` default
* This branch of the ladder: 1241156c82/synapse/rest/key/v2/remote_key_resource.py (L192)
* Returning empty arrays when querying offline/no servers
* Queried by hand against matrix.org as a notary server with a fake domain name to query
* Returning all keys even when querying for specific keys
* Queried by hand using matrix.org as a notary server against a server publishing multiple keys.
The examples and descriptions were also improved as part of this commit.
