Generally speaking the documentation for all sister projects lives in that project's sourceforge repository under trunk/main/documentation. For example, the documentation for the Star Objects project resides in the Star Objects repository under trunk/documentation.

As always, use Subversion to check out. For example:

svn co https://starobjects.svn.sourceforge.net/svnroot/starobjects/trunk/main/documentation ~/starobjects/trunk/main/documentation