Currently, Diviner is only really useful for generating Phabricator documentation. Eventually, it would be nice to make it useful for projects in general. Work on T988 has made major strides toward this goal, but significant work remains, especially to support languages other than PHP and Javelin-flavored Javascript.
This is not a priority for us, but if you're interested we'd love to hear about your use case and which languages you'd like to generate documentation for.