Update config doc
Update config doc

original-commit-id: a114b6426ec77cbaf2066ab25b68b5a5f7518341
original-commit-url: https://github.com/ipython-contrib/IPython-notebook-extensions/commit/a114b6426ec77cbaf2066ab25b68b5a5f7518341

jcb91/jupyter_nbextensions_configurator,jcb91/jupyter_nbextensions_configurator,jcb91/jupyter_nbextensions_configurator,jcb91/jupyter_nbextensions_configurator