Minor update to the VTT materials

Just a quick explanation of the latest update: I tweaked some wording in the PDF included in the virtual tabletop materials guide, noting that opinions on whether or not the Rider-Waite Smith tarot set is within the public domain may differ from country to country. I'm not a lawyer, but I've done my own research into my country's copyright laws (Australia), and to the best of my knowledge I am compliant with them. What I don't want is folx using the cards for their own commercial purposes and then relying on my advice here. If you do use the material that I've personally deemed within the public domain for my own use case, please do your own research on whether or not the same applies to you.