Fixes YOCTO #4753
This is the main change to address this bug. It is a new section
that describes how the user can get a buildtools tarball if their
system does not meet the proper Git, tar, and Python versioning.
(From yocto-docs rev: 0493a55c85f050ba29f605ab727e557849242bae)
Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>