The wiki area of your open source project is open to all logged in Wikidot.com users to edit. They can create pages and edit existing pages.
In this way, your users can help to formulate documentation when it is in a very early stage — and you can move it to the Docs when it is complete.
There are many other uses an open Wiki can provide for your project. If you leave the permissions as they are so that anyone can contribute, your users might surprise you ;-)