Nbdev and package_data

I’m having no luck in adding package_data using just MANIFEST.in. At least it’s missing in the tar file still.
Considering this SO issue python - How to include package data with setuptools/distutils? - Stack Overflow this is still all such a mess, I was wondering what are the best ways to add package_data (config files in my case that I have in lib_name/data) to the distribution using nbdev?