- 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

 - Update the asking questions page
 - Update the side projects page

* 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

I didn't have cmake installed on arch, and my build failed. Thought it should be included in the book

Since Bell Labs has died, the Plan9 project website only exists at a
mirror on 9p.io

"Null-terminated" is the more common term, and I think better suited to denote that the string (being the object) is being terminated by a null. Feel free to edit my commit in that regard, if you prefer the current ending.

"a URL…" being singular.

The "Programs and Libraries" link in TOC doesn't work, this should fix it.

I'm guessing, question marks indicate where I know I'm guessing.

new name of mac's system

In section 3.1 'Preparing Redox', the book suggests using the cross compilers from glendc/gcc_cross_compilers. These no longer work, and are not being used in the bootstrap.sh script from the redox-os/redox repo. This closes redox-os/book#84.

Current output is \$identifier.
Additional quote removed
Additional # stdout added for John example