morphologica reference
The ultimate reference source for the classes in morphologica is the headers themselves. In many cases the headers are easy to read because the code is not split up into header/implementation.
There is also the possibility of generating doxygen reference pages from the code comments. Although I don’t think doxygen-generated reference material is much easier to learn from than the headers themselves, they can be built (and may be linked to this site, too, in future).
These reference pages are hand-written and should provide a quick-to-browse summary of the details of each class.