Updated the project's README

* removed golangci badge
* made it explicit the repo won't support swagger 3

* closes go-openapi#21

Signed-off-by: Frederic BIDON <fredbi@yahoo.com>

README.md

@@ -2,9 +2,12 @@
 
 [![license](http://img.shields.io/badge/license-Apache%20v2-orange.svg)](https://raw.githubusercontent.com/go-openapi/spec/master/LICENSE)
 [![GoDoc](https://godoc.org/github.com/go-openapi/spec?status.svg)](http://godoc.org/github.com/go-openapi/spec)
-[![GolangCI](https://golangci.com/badges/github.com/go-openapi/spec.svg)](https://golangci.com)
 [![Go Report Card](https://goreportcard.com/badge/github.com/go-openapi/spec)](https://goreportcard.com/report/github.com/go-openapi/spec)
 
 The object model for OpenAPI specification documents.
 
-Currently supports Swagger 2.0.
+This currently only supports Swagger 2.0.
+
+No plan is intended to make it support Swagger 3.x.
+
+An early attempt to support Swagger 3 may be found at: https://github.com/go-openapi/spec3