If you're asking about the site itself, not the site's contents, it's probably off-topic. From the close dialog:
This question does not appear to be about science fiction or fantasy within the scope defined in the help center.
And from that link, we see types of questions that are on-topic:
Plot, character, or setting explanations
Historical or societal context of a work
Behind-the-scenes and fandom information
- Story identification
- Franchise/series reading or viewing order
The only thing here that this type of question could fall into is
behind-the-scenes and fandom information, but this is more referring to questions surrounding the development of the particular story or world.
I don't know much about your particular example, but unless whatever world that particular site talks about is the main source for the lore of that world, it's probably off-topic. For a slightly more detailed explanation of what constitutes "behind-the-scenes", see here. Even so, such a question would need to be constrained so as to focus on the development of the lore.
TL;DR: If your question deals with solely a website, it's probably off-topic, unless that website was used as a vehicle for the development of the story.