Expanding on the sandbox docs

Figuring out what was actually going on in the sandbox took a bit of time and some googling. It would have been helpful for it to note exactly what was meant by the optional context. I've updated it to include a quick start for people using it with modules and such. I'm not sure if this is the proper place/formatting for that doc but the sandbox being an extremely powerful tool should have a bit more documentation to help people get off the ground with it.