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/virtualisation/openvswitch.nix

@@ -31,6 +31,7 @@ in {
     package = mkOption {
       type = types.package;
       default = pkgs.openvswitch;
+      defaultText = "pkgs.openvswitch";
       description = ''
         Open vSwitch package to use.
       '';