Add example notebooks to hyswap repository
This MR adds the necessary sphinx details to host Jupyter notebooks both in the documentation and in a folder on the hyswap repository.
It contains the Jupyter notebooks in an "example_notebooks" file that is easily found by users of the package on the hyswap GitHub. Within that folder is also an "example_data" folder that contains the intersection table used in the runoff example notebook.
I updated the README.md to contain info about using the example notebooks.
Edited by Hinman, Elise D