You can have as detailed help as you want in How to use this site thread in “New to Community” category. That is proper place for documenting site functions… The thread is already pinned to appear on top. Besides it is way easier and quicker to read one thread than dozens of different threads.
Creation of too many categories leads to chaos as people don’t know which category to choose when posting.
Right now I will refrain from creating new categories and see how things work. It is easier to create new category when time shows that it is really needed, then to delete categories.