Clarification on how to begin calibration

No underscores in host name

I tried to run calibration by going into the donkey environment on my Mac instead of ssh-ing into my Pi. Hopefully adding this line will enable others to avoid my mistake and wasting time.

Update instructions - no hyphens in host name

Using underscore in the host name prevents you from pinging it via host name. Updating instructions to indicate no underscores.

According to RFC 1123, section 2.1 "Host Names and Numbers" host names are limited to just letters, digits, and hyphens.

* Documentation changes to add new TT01 Hardware

* Changes to clean up docs, update parts and add Desert Monster as a standard build

* try circleci

* add new circle ci badge

Added lines 227 to 231 to remind folk to install gcc / Apple's Command Line for Tools for Xcode if user hasn't either installed.

and what to look for in cars you want to use.

Also add a link to said document.

fixes #220

Correct spelling mistakes.

Probably want to delete gitconfig otherwise people will be submitting changes to their cloned repos as will roscoe :D