new name of mac's system

Propose three categories names for Redox side projects

Added more concrete documentation for compiling test binaries for redox

Updating macOS cross compilers

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 #84.

STDOUT would be $identifier

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

Update preparing_the_build.md

mdBook uses pulldown-cmark. pulldown-cmark implements CommonMark. CommonMark, unlike Github Markdown, needs a space after # for ATX style headers. See http://spec.commonmark.org/0.27/#atx-headings

Update preparing_the_build.md

Elaborate the use of the bootstrap script. Include a word of caution in case dependencies already exist on the system and are skipped by bootstrap. Restructure the chapter to better distinguish between a manual setup and a script based setup.

Add note about error management in 'rusting_properly.md'

closes #78

Signed-off-by: Jerome Jutteau <mojo@couak.net>

Add a graphical overview of Redox boot process

Signed-off-by: Jerome Jutteau <mojo@couak.net>

Update exploring_redox.md

Improved the language in the "Exploring OrbTK" section.

Add a more accurate description of tfs in the overview

Add hardware that supporting Redox

Review entirely the 'Overview' part

Add README file and hyperlinks