[coi] COI server specifications

[Timo Sirainen]

Hi everyone,

I’m pleased to announce that we have now published the COI server side specification. The following specifications are now available at https://github.com/coi-dev/coi-specs:

 - COI slient spec
 - COI server spec
 - Submission Token Extension draft

Still missing is the IMAP WebPush Extension specification, which will be published within the next weeks.

- Timo