nixos/*: unhide remaining systemd stage-1 options

These options were missed in NixOS/nixpkgs#226237, but they all were
specifically added for systemd stage-1.

nixos/modules/config/users-groups.nix

···
 
     # systemd initrd
     boot.initrd.systemd.users = mkOption {
-      visible = false;
       description = ''
         Users to include in initrd.
       '';
       default = {};
       type = types.attrsOf (types.submodule ({ name, ... }: {
         options.uid = mkOption {
-          visible = false;
           type = types.int;
           description = ''
             ID of the user in initrd.
···
           default = cfg.users.${name}.uid;
         };
         options.group = mkOption {
-          visible = false;
           type = types.singleLineStr;
           description = ''
             Group the user belongs to in initrd.
···
     };
 
     boot.initrd.systemd.groups = mkOption {
-      visible = false;
       description = ''
         Groups to include in initrd.
       '';
       default = {};
       type = types.attrsOf (types.submodule ({ name, ... }: {
         options.gid = mkOption {
-          visible = false;
           type = types.int;
           description = ''
             ID of the group in initrd.

nixos/modules/services/hardware/udev.nix

···
       packages = mkOption {
         type = types.listOf types.path;
         default = [];
-        visible = false;
         description = lib.mdDoc ''
           *This will only be used when systemd is used in stage 1.*
 
···
       binPackages = mkOption {
         type = types.listOf types.path;
         default = [];
-        visible = false;
         description = lib.mdDoc ''
           *This will only be used when systemd is used in stage 1.*
 

nixos/modules/services/system/dbus.nix

···
   options = {
 
     boot.initrd.systemd.dbus = {
-      enable = mkEnableOption (lib.mdDoc "dbus in stage 1") // { visible = false; };
+      enable = mkEnableOption (lib.mdDoc "dbus in stage 1");
     };
 
     services.dbus = {

nixos/modules/tasks/bcache.nix

···
 { config, lib, pkgs, ... }:
 
 {
-  options.boot.initrd.services.bcache.enable = (lib.mkEnableOption (lib.mdDoc "bcache support in the initrd")) // {
-    visible = false; # only works with systemd stage 1
+  options.boot.initrd.services.bcache.enable = lib.mkEnableOption (lib.mdDoc "bcache support in the initrd") // {
+    description = lib.mdDoc ''
+      *This will only be used when systemd is used in stage 1.*
+
+      Whether to enable bcache support in the initrd.
+    '';
   };
 
   config = {

nixos/modules/tasks/lvm.nix

···
     boot.vdo.enable = mkEnableOption (lib.mdDoc "support for booting from VDOLVs");
   };
 
-  options.boot.initrd.services.lvm.enable = (mkEnableOption (lib.mdDoc "enable booting from LVM2 in the initrd")) // {
-    visible = false;
+  options.boot.initrd.services.lvm.enable = mkEnableOption (lib.mdDoc "booting from LVM2 in the initrd") // {
+    description = lib.mdDoc ''
+      *This will only be used when systemd is used in stage 1.*
+
+      Whether to enable booting from LVM2 in the initrd.
+    '';
   };
 
   config = mkMerge [

nixos/modules/tasks/swraid.nix

···
 in {
 
   options.boot.initrd.services.swraid = {
-    enable = (lib.mkEnableOption (lib.mdDoc "swraid support using mdadm")) // {
-      visible = false; # only has effect when the new stage 1 is in place
+    enable = lib.mkEnableOption (lib.mdDoc "swraid support using mdadm") // {
+      description = ''
+        *This will only be used when systemd is used in stage 1.*
+
+        Whether to enable swraid support using mdadm.
+      '';
     };
 
     mdadmConf = lib.mkOption {