Documentation is part of wiki pages as per now, you can see it at

http://brlcad.org/wiki/Documentation

The task requires you to create a graphical or HTML & CSS/SASS mockup for the documentation page of BRL-CAD. As it is a wiki page so the mock up created for wiki pages can be used. It should be consistent with main wiki design but at same time different from rest of wiki pages. You can incorporate some content from BRL-CAD's doc book too.