Docs have a special page and a slightly different layout, but are built from regular topics. You can check out ours here on Meta Docs. This is the docs version of one https://meta.discourse.org/docs?topic=224824 and this is the topic Trust Level Permissions Table (inc Moderator Roles) 
A topic is a collection of posts linked together to make a conversation. This discussion we’re now having, for example, is a topic consisting of individual posts.