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/system/activation/top-level.nix

@@ -205,7 +205,7 @@ in
 
     system.replaceRuntimeDependencies = mkOption {
       default = [];
-      example = lib.literalExample "[ ({ original = pkgs.openssl; replacement = pkgs.callPackage /path/to/openssl { ... }; }) ]";
+      example = lib.literalExample "[ ({ original = pkgs.openssl; replacement = pkgs.callPackage /path/to/openssl { }; }) ]";
       type = types.listOf (types.submodule (
         { options, ... }: {
           options.original = mkOption {

nixos/modules/system/boot/kernel.nix

@@ -20,6 +20,7 @@ in
   options = {
 
     boot.kernelPackages = mkOption {
+      type = types.packageSet;
       default = pkgs.linuxPackages;
       # We don't want to evaluate all of linuxPackages for the manual
       # - some of it might not even evaluate correctly.
@@ -63,7 +64,7 @@ in
     };
 
     boot.extraModulePackages = mkOption {
-      type = types.listOf types.path;
+      type = types.listOf types.package;
       default = [];
       example = literalExample "[ pkgs.linuxPackages.nvidia_x11 ]";
       description = "A list of additional packages supplying kernel modules.";

nixos/modules/system/boot/loader/grub/grub.nix

@@ -251,6 +251,7 @@ in
       };
 
       extraFiles = mkOption {
+        type = types.attrsOf types.path;
         default = {};
         example = literalExample ''
           { "memtest.bin" = "''${pkgs.memtest86plus}/memtest.bin"; }

nixos/modules/system/boot/loader/grub/ipxe.nix

@@ -39,7 +39,7 @@ in
               dhcp
               chain http://boot.ipxe.org/demo/boot.php
             ''';
-          };
+          }
         '';
       };
     };

nixos/modules/system/boot/luksroot.nix

@@ -229,7 +229,7 @@ in
 
     boot.initrd.luks.devices = mkOption {
       default = [ ];
-      example = [ { name = "luksroot"; device = "/dev/sda3"; preLVM = true; } ];
+      example = literalExample ''[ { name = "luksroot"; device = "/dev/sda3"; preLVM = true; } ]'';
       description = ''
         The list of devices that should be decrypted using LUKS before trying to mount the
         root partition. This works for both LVM-over-LUKS and LUKS-over-LVM setups.

nixos/modules/system/boot/systemd.nix

@@ -374,6 +374,7 @@ in
 
     systemd.package = mkOption {
       default = pkgs.systemd;
+      defaultText = "pkgs.systemd";
       type = types.package;
       description = "The systemd package.";
     };