Merge pull request #278500 from Ten0/fix_avahi_ipv6_defaultText

nixos/avahi: fix incorrect defaultText of nixos option services.avahi.ipv6

nixos/modules/services/networking/avahi-daemon.nix

···
     ipv6 = mkOption {
       type = types.bool;
       default = false;
-      defaultText = literalExpression "config.networking.enableIPv6";
       description = lib.mdDoc "Whether to use IPv6.";
     };