Sorry Peter, I don't like that variant and want to stick with a separate customization step that uses **kwds so we can use normal syntax for the name value pairs and to allow that possibility of someone passing in an existing dict using NT.set_docstrings(**d).

Also FWIW, the addition can be simplified a bit when Issue 24064 is added:

        for fieldname, docstring in docstrings.items():
            getattr(cls, fieldname).__doc__ = docstring