Explicitly state when something in undocumented
Explicitly state when something in undocumented

In get_doc(), if we don't get any documentation for something, we'll
output `<undocumented>`. The main reason for this is so that
autosummary tables don't show broken 'more...' links, because they get
the first sentence or so of documentation.

angus-g/sphinxcontrib-autodoc_doxygen