Add session-desktop.

nodes/hosts/common/configuration.nix

@@ -6,6 +6,7 @@
     ./programs/general.nix
     ./programs/git.nix
     ./programs/kde.nix
+    ./programs/session-desktop.nix
     ./programs/steam.nix
     ./programs/zen-browser.nix
     ./scripts/upgrade-diff.nix

nodes/hosts/common/programs/session-desktop.nix

@@ -0,0 +1,8 @@
+{ pkgs, ... }: {
+  # List packages installed in system profile. To search, run:
+  # $ nix search wget
+  environment.systemPackages = [
+    pkgs.session-desktop
+  ];
+}
+