How do I include the Description from the Inventory Widget in the notification email template?

My guess is that i would include it in brackets into the content of the e-mail notification settings?

I'm sorry, but you cannot have the description from the inventory widget in the notification email. You will have to manually put the texts if you want to receive them beside the widget label. Note that putting the texts will void the Auto Hide Empty Fields in the email template which means that empty fields/widgets will still appear in the email.