Complete docs

[nirs]

We have initial docs directory with some content duplicated from the README.md and examples/README. We need to remove the duplication, and improve the layout.

When we write the docs, we should consider the audience:

• Teachers - may want to use this project in their classroom
• Students - may want to write a driver module
• Developers that may like to contribute to the project
• Maintainers that want to cut a release
• Other?

Looking in the github traffic report, we can see that the main README page is the most
popular page. So we want everything linked from this page.

When a user visit the docs, they may like to go back to the project in github, we want a link
from the docs back to the project.

Possible layout (role based)

• README.md
  • simple overview of the project, no details
  • video/pictures/live demo, make it fun
  • links to most docs in github.io
• docs/index.md - show all the available docs
• docs/teachers.md - docs for teachers
• docs/students.md - docs for students
• docs/contributing.md - docs for developers
• docs/release.md - docs for maintainers