One more suggest from me. Hope I'm not impudent, well not yet :)
Docstring is a cool feature, and with it we don't have to describe out tests somewhere else istead of test itself. I would suggest to read docstring from class/function and append it to the title here:
https://github.com/davehunt/pytest-html/blob/master/pytest_html/plugin.py#L154
optionally. Optionally, because when someone wants to perform doctest (dunno if there someone which does :) ), the feature will destroy the report.