include all items doc/ in sdists

https://files.pythonhosted.org/packages/51/31/85cb6129d22c75722d1e1a8db0cdaf36ab7e1e7a59189bfa275445c8ab2d/nbsphinx-0.9.3.tar.gz
is missing quite a few number of files

Author: mr-c

MANIFEST.in

@@ -1,10 +1,4 @@
 include LICENSE
 include *.rst
-include doc/requirements.txt
-include doc/conf.py
-include doc/*.rst
-include doc/*.ipynb
-include doc/subdir/*.ipynb
-include doc/images/*
-include doc/references.bib
-include doc/ipython_kernel_config.py
+include doc/requirements.txt doc/references.bib
+recursive-include doc *.ipynb matplotlibrc *.md *.rst *.py *.txt *.svg *.png