Where to add system packages in the "Nix Starter Config"?

I have been looking at Misterio77’s minimal and standard Nix Starter Config, trying to figure out how to best organise my config files.

To me, it looks like a user’s packages is defined under home-manager, in home.nix. However, I can not see where one should add system packages (as in environment.systemPackages = with pkgs; [ ]).

If one use this way of configuring the system, where would be a logical place to add system packages?

In nixos/configuration.nix