Add yaml files for jupyter_nbextensions_configurator

[jcb91]

As requested in ipython-contrib/jupyter_contrib_nbextensions#489 (comment), this is a reminder to add yaml files for jupyter_nbextensions_configurator.

[jcb91]

I'm not really sure where this might go, given the current package structure. Given nbpresent/tasks/index.py#L12-L15 and nbpresent/tasks/_env.py#L14-L15, I suspect either DIST or JS, but not sure which would be appropriate.

[damianavila]

ping @bollwyvl

[linwoodc3]

Is there anything I can do to help; hate to be a guy to kinda suggests something and not help. Open source is all about helping right?