Merge pull request #235387 from doronbehar/nixos/nextcloud.adminpassFile

nixos/nextcloud: Mention that adminpassFile is only used on startup

nixos/modules/services/web-apps/nextcloud.nix

···
         type = types.str;
         description = lib.mdDoc ''
           The full path to a file that contains the admin's password. Must be
-          readable by user `nextcloud`.
+          readable by user `nextcloud`. The password is set only in the initial
+          setup of nextcloud by the systemd `nextcloud-setup.service`.
         '';
       };