Add missing 'type', 'defaultText' and 'literalExample' in module definitions

- add missing types in module definitions
- add missing 'defaultText' in module definitions
- wrap example with 'literalExample' where necessary in module definitions

nixos/modules/services/misc/confd.nix

@@ -64,6 +64,7 @@ in {
     package = mkOption {
       description = "Confd package to use.";
       default = pkgs.confd;
+      defaultText = "pkgs.confd";
       type = types.package;
     };
   };