* Fix spelling: github -> GitHub, etc.
* Update the GitHub team list
* Move `null:` and `zero:` to the userspace schemes
* Change icons from Oxygen to Faba/Moka
* Remove statements that TFS is a ZFS implementation
* Add Intel HDA to the supported hardware
* Remove the `libredox` guideline
* Add some outgoing links where I think they're necessary

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.