Add obsoletion notice

Author: andreubotella

README.md

@@ -3,3 +3,5 @@
 This repository contains changes to the WHATWG Fetch standard to make it more suitable to server side runtimes.
 These changes will soon be, or are in the process of being upstreamed to the [WHATWG fetch standard](https://fetch.spec.whatwg.org/).
 
+This fork is no longer being worked on, and any further needs in that area are expected to be met by contributing to the upstream standard.
+

fetch.bs

@@ -8,6 +8,9 @@ URL: https://fetch.spec.wintercg.org/
 Repository: https://github.com/wintercg/fetch
 Editor: Ethan Arrowood, Vercel http://vercel.com, ethan-arrowood@vercel.com
 Abstract: A fork of the WHATWG Fetch standard that defines requests, responses, and the process that binds them: fetching.
+Warning: custom
+Custom Warning Title: This fork is no longer being developed
+Custom Warning Text: The changes in this fork with respect to the <a href="https://fetch.spec.whatwg.org">WHATWG Fetch standard</a> are expected to be upstreamed if they haven't been already, and any further needs in that area are expected to be met by contributing upstream.
 Markup Shorthands: css off
 Translate IDs: typedefdef-bodyinit bodyinit,dictdef-requestinit requestinit,typedefdef-requestinfo requestinfo,enumdef-requestdestination requestdestination,enumdef-requestmode requestmode,enumdef-requestcredentials requestcredentials,enumdef-requestcache requestcache,enumdef-requestredirect requestredirect,dictdef-responseinit responseinit,enumdef-responsetype responsetype
 </pre>