Organize README.md and CONTRIBUTING.md

Created by: polymetric1

I removed the inconsistent and unorganized multiplatform build instructions in favor of two instruction sets, quick setup and manual setup. Quick setup uses bootstrap.sh, and manual setup just lists all the commands you need to do it manually. This should make it alot more simple and easy for beginners, as well as more advanced users.

The diff is a bit hard to read, you can just look at the final changed files here https://github.com/polymetric1/redox/blob/contributing-md/README.md https://github.com/polymetric1/redox/blob/contributing-md/CONTRIBUTING.md