Add screenshots / usage tutorial documentation

[justwheel]

I found the project and was curious about how it worked or what it looked like, but I couldn't find any examples of screenshots, usage documentation, or explanations of how the application works. I would be interested to know more about how the application works, whether in the README or in standalone documentation.

[sumnerevans]

@jflory7 , we are planning on adding standalone Sphynx documentation (#58). Until we get that up, if you want to view a site that is running this code, see https://acm.mines.edu/.