Swagger & OpenAPI

Goal is to support both Swagger & OpenAPI specifications for route documentation.

Swagge-support draft works, but only for Clojure.

TODO:

• metosin/schema-tools#38: extract Schema-swagger from ring-swagger into schema-tools to support both Clojure & ClojureScript
• separate modules for the swagger2 & openapi
• metosin/spec-tools#105: support OpenApi