Separated out shared.nix into headful and headless nix config files

config/user.nix

@@ -0,0 +1,8 @@
+# Generic user configuration.
+# Don't forget to set a password with ‘passwd’.
+{
+  isNormalUser = true;
+  useDefaultShell = true;
+  description = "random";
+  extraGroups = [ "networkmanager" "wheel" "docker" ];
+}