Reflect that this repo is work in progress.

The phrasing make it seem like this repo contains the source for the versioned instances of the specification, which is not the case. Trying to make it clearer.

Author: Relequestual

README.md

@@ -2,7 +2,8 @@
 
 JSON Schema is a vocabulary that allows you to validate, annotate, and manipulate JSON documents.
 
-This repository contains the sources for current JSON Schema draft work.
+This repository contains the sources for the **work in progress** of the next JSON Schema IETF Internet Draft (ID) document.
+For released versions, please see the [Previous Versions](#previous-versions) section.
 
 ## Call for reviews