Updated documentation index file to display more levels in the table of contents.
Updated documentation index file to display more levels in the table of contents.

hjanime/VisTrails,minesense/VisTrails,hjanime/VisTrails,Nikea/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,Nikea/VisTrails,hjanime/VisTrails,hjanime/VisTrails,VisTrails/VisTrails,minesense/VisTrails,minesense/VisTrails,Nikea/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,VisTrails/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,minesense/VisTrails,hjanime/VisTrails,celiafish/VisTrails,minesense/VisTrails,Nikea/VisTrails