Add lego-style instructions

[ldang]

The Beyond Robotics FTC team made a Google doc with lego-style instructions based on the OnShape model.

I think we can incorporate this into the our current repo by using pandoc to convert it to Markdown. I'm not sure where it should fit in the repo structure and how to get it into read-the-docs.

[igillespie]

As someone who just ordered all of the parts to build this at home with two kids. These instructions make this project seem way more doable. Thank you!