Improve Contributing Documentation

[ljlamarche]

Currently instructions for how to contribute are limited to a small portion of the README. Expand these to include the actual commands that need to be run to set up an environment, build the book, ect. Also set up templates for users to submit different kinds of issues?

[ljlamarche]

It would probably work to add these more detailed instructions to the book itself, possibly under a "Contributing" or "Development" section. Also add more general instructions for users to download the book, set up an environment, and run it locally.

[ljlamarche]

Better instructions for basic contributions to the book have been added to the README c7418b4