Automatically load autosummary (#143)

Fix #141

Author: jnothman

doc/install.rst

@@ -9,8 +9,8 @@ The extension is available from:
 * `numpydoc on GitHub <https://github.com/numpy/numpydoc/>`_
 
 'numpydoc' should be added to the ``extensions`` option in your Sphinx
-``conf.py``.
-
+``conf.py``. (Note that `sphinx.ext.autosummary` will automatically be loaded
+as well.)
 
 Sphinx config options
 =====================

numpydoc/numpydoc.py

@@ -151,6 +151,8 @@ def setup(app, get_doc_object_=get_doc_object):
     app.add_domain(NumpyPythonDomain)
     app.add_domain(NumpyCDomain)
 
+    app.setup_extension('sphinx.ext.autosummary')
+
     metadata = {'version': __version__,
                 'parallel_read_safe': True}
     return metadata