When you click that Tracker Option button, you can create another meal plan category. Those people have created a category for their supplements, so they don't have to show up in breakfast, lunch or dinner. But they still had to add the actual supplement the same way I described below.
Hope that helps,
"You may have a fresh start any moment you choose, for this thing that we call "failure" is not the falling down but the staying down." Mary Pickford