JSON API for documentation state

[tayloraswift]

usage example:

$ curl \
    -H "Authorization: Unidoc 4297524282_184d38185839950a" \
    https://localhost:8443/ref/swift-json/1.0.1/state

{"id":1,"volume":"swift-json:1.0.1","graph":{"commit":"22ffd76580e58d8e99dcabc8521d80bbf71eaffa"},"phase":"ACTIVE"}

authorization header has form \(userID)_\(apiKey)

i’m not sure if this fully solves the CI workflow problem. but reading the JSON is much easier than parsing /tags page HTML.

the JSON schema is defined here and we will need to document it