document IPinfo sponsorship

Author: thestinger

static/articles/grapheneos-servers.html

@@ -68,6 +68,15 @@ <h2><a href="#ns1.grapheneos.org">GrapheneOS DNS servers</a></h2>
                     <li><a href="https://github.com/GrapheneOS/ns1.grapheneos.org/issues">Issue tracker</a></li>
                 </ul>
 
+                <p>Our authoritative DNS servers implement GeoDNS with a local GeoIP database from a
+                sponsorship by <a href="https://ipinfo.io/">IPinfo</a>. IPinfo primarily uses over
+                1300 probe locations to build their GeoIP database based on measurements rather than
+                the traditional approach used by most GeoIP companies of building it with WHOIS data
+                including geofeeds which are often missing or outdated. A free version of their
+                database (IPinfo Lite) is available on GitHub with country data. They provide use
+                with their premium IP to Geolocation Database with region codes and cities which we
+                use to direct users within large countries to the best server location.</p>
+
                 <p>Specs:</p>
 
                 <ul>