- Update to latest mdbook
   - Switch to using book.toml
   - No empty links are allowed anymore. Comment out all empty links in
     SUMMARY.md
 - Add theme
   - Add favicon.png

Ben Elliott authored 8 years ago and Jeremy Soller committed 8 years ago

This contribution adds information for contributors (which fills
in some missing sections in the book). Meta!

I copied a lot of this from the main Redox project's CONTRIBUTING.md,
with minimal changes where appropriate. Also, some small additions.