autosummary fails with numpydoc where napoleon succeeds

[mattip]

In merging randomgen to numpy, I changed from napoleon to numpydoc and the build could not link to autogenerated docs.

Here is the diff

diff --git a/doc/source/conf.py b/doc/source/conf.py
index d4290d17..6fd7bcb5 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -43,8 +43,9 @@ release = randomgen.__version__
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
 extensions = [
-    'sphinx.ext.napoleon',
+    #'sphinx.ext.napoleon',
     'sphinx.ext.autodoc',
+    'numpydoc',
     'sphinx.ext.extlinks',
     'sphinx.ext.todo',
     'sphinx.ext.doctest',

And here are the top few warnings, there are thousands more

building [mo]: targets for 0 po files that are out of date
building [html]: targets for 198 source files that are out of date
updating environment: 198 added, 0 changed, 0 removed
reading sources... [100%] references                                                                                                          
docstring of randomgen.dsfmt.DSFMT:105: WARNING: toctree references unknown document 'brng/randomgen.dsfmt.DSFMT.jump'
docstring of randomgen.dsfmt.DSFMT:105: WARNING: toctree references unknown document 'brng/randomgen.dsfmt.DSFMT.random_raw'
docstring of randomgen.dsfmt.DSFMT:105: WARNING: toctree references unknown document 'brng/randomgen.dsfmt.DSFMT.seed'
...

Any hints?

[mattip]

Duplicate of #184