dns-root-data: add missing homepage (#396613)

Co-authored-by: Sandro <[e-mail]>

pkgs/by-name/dn/dns-root-data/package.nix

···
   '';
 
   meta = with lib; {
+    homepage = "https://www.iana.org/domains/root/files";
     description = "DNS root data including root zone and DNSSEC key";
     maintainers = with maintainers; [
       fpletz