ARC: Rewrite README.ARC

Many changes to doc/README.ARC:
* Convert it to Markdown format instead of some custom formatting
* Remove unused software from the list of installation prerequisites
* Remove content that was just duplicating output of “help” commands of
  different applications
* Change build instruction for Linux and Windows. Describe new ftdi
  interface
* Add section on running on Windows and installing WinUSB drivers
* Many smaller changes.

Signed-off-by: Anton Kolesov <anton.kolesov@synopsys.com>