The documentation for redmine_taskjuggler is available in the README.rdoc file at the top of the repository, and it the various files (markdown, rdoc, textile, txt) in the ./doc/ subfolder (including CREDITS, LICENSCE, etc.).
The purpose of this wiki is more of a scratchpad for stuff to be included later in the documentation folder or elsewhere.
There is also a feature on GitHub for creating a website. That seems like a particularly interesting feature. If the website can be the guide, than that would be just dandy.