gnu-social/socialfy-your-domain/dot-well-known/host-meta

<?xml version="1.0" encoding="UTF-8"?>
<XRD xmlns="http://docs.oasis-open.org/ns/xri/xrd-1.0"
     xmlns:hm="http://host-meta.net/xrd/1.0">  
  <hm:Host>example.com</hm:Host>
  <Link rel="lrdd" template="http://example.com/.well-known/xrd?uri={uri}">
    <Title>WebFinger resource descriptor</Title>
  </Link>
</XRD>