Simply use class names as option help
The justification for this is that 1) the options are
already documented in the API documentation and 2) the
class names are fairly self-explanatory, so adding short
descriptions doesn't add much.
In the future, however, we could add a short description
by simply using the first line or sentence of the docstring;
note that docstrings would have to be canonicalized, which
they aren't now.