adding desktop config

modules/nixos/bspwm.nix

@@ -0,0 +1,20 @@
+{ pkgs, ... }:
+
+{
+  services.xserver = {
+    enable = true;
+    windowManager.bspwm = {
+      enable = true;
+      configFile = "/home/chris/.config/bspwm/bspwmrc";
+      sxhkd.configFile = "/home/chris/.config/sxhkd/sxhkdrc";
+    };
+    displayManager.lightdm.enable = true;
+  };
+
+  services.displayManager.defaultSession = "none+bspwm";
+
+  environment.systemPackages = with pkgs; [
+    xterm
+    dmenu
+  ];
+}