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/apache-kafka.nix

@@ -118,9 +118,8 @@ in {
 
     package = mkOption {
       description = "The kafka package to use";
-
       default = pkgs.apacheKafka;
-
+      defaultText = "pkgs.apacheKafka";
       type = types.package;
     };