Just a quick note: many sites use the "What topics can I ask about here?" page to enumerate both things that are explicitly on-topic for the site and subjects that may appear to an outside user to be on-topic but which the community has decided are out of scope. You can do them both in a list format for easy reading. Take Super User's, for example:
Super User is for computer enthusiasts and power users. If you have a
question about …
- computer hardware,
- computer software, or
- personal and home computer networking
and it is not about …
- programming and software development,
- video games or consoles,
- websites or web services like Facebook, Twitter, and WordPress,
- electronic devices, media players, cell phones or smart phones, except insofar as they interface with your computer,
- issues specific to corporate IT support and networks,
- asking for a shopping or product recommendation
… then you’re in the right place to ask your question!
You don't have to do it this way, but it's a great way to disambiguate any quirks related to this particular community. (For example, if gardening questions are off-topic here, even if you are gardening as a way to have a more sustainable lifestyle, that would be a great thing to put on this page). The "What types of questions should I avoid asking?" page provides guidance on style of question (no shopping recommendations, guidelines for good v. bad subjective questions, etc.) than it does subject matter. That page is the same for every Stack Exchange site.