Implement initial containers module

nixos/modules/server.nix

@@ -1,7 +1,7 @@
-{ config, lib, ... }:
+{ lib, pkgs, config, ... }:
 let
   inherit (lib) mkIf mkDefault;
-  inherit (lib.my) mkBoolOpt';
+  inherit (lib.my) mkBoolOpt' mkDefault';
 
   cfg = config.my.server;
   uname = if config.my.user.enable then config.my.user.config.name else "root";
@@ -17,6 +17,12 @@ in
     my.user.homeConfig = {
       my.gui.enable = false;
     };
+
+    documentation.nixos.enable = mkDefault' false;
+
+    environment.systemPackages = with pkgs; [
+      tcpdump
+    ];
   };
 
   meta.buildDocsInSandbox = false;