nixos/inadyn: fix defaultText (#384773)

Author: SuperSandro2000

nixos/modules/services/networking/inadyn.nix

@@ -146,7 +146,7 @@ in
           options = {
             allow-ipv6 = lib.mkOption {
               default = config.networking.enableIPv6;
-              defaultText = "`config.networking.enableIPv6`";
+              defaultText = lib.literalExpression "config.networking.enableIPv6";
               description = "Whether to get IPv6 addresses from interfaces.";
               type = bool;
             };