Add a basic README

Author: tianon

README.md

@@ -0,0 +1,5 @@
+# `import "github.com/docker-library/go-dockerlibrary/manifest"`
+
+[![Travis Build Status](https://travis-ci.org/docker-library/go-dockerlibrary.svg?branch=master)](https://travis-ci.org/docker-library/go-dockerlibrary) [![GoDoc](https://godoc.org/github.com/docker-library/go-dockerlibrary?status.svg)](https://godoc.org/github.com/docker-library/go-dockerlibrary)
+
+This package contains the core parsing elements of [the `bashbrew` tool used by the Docker Official Images](https://github.com/docker-library/official-images/tree/master/bashbrew).