There is no need to add this to the Help Center.
This information is contained right within the Tour.
Board & Card Games Stack Exchange is a question and answer site for people who like playing board games, designing board games or modifying the rules of existing board games.
The on-topic section is attempting to define the boundaries of our charter. As well as excise certain topics within that charter.
Your question is not directly aimed at our charter. A board game expert would not be the best person to answer your question, you need a lawyer.
I should note that not every question that fails to directly score on our charter should be closed. It is up to the community to make that judgement on a case by case basis. As a moderator I'm not likely to overrule such decisions very often.
Consider a couple fake questions:
- How can I safely store my huge MtG card collection?
- Are MtG cards safe to feed to my hamster?
Both questions are superficially about MtG, but you wouldn't need to be knowledgeable about the game to answer the questions authoritatively. I'd expect one question to be answered, and the second to get closed pretty quickly.