Add documentation for bitbake-setup. This is split in 6 sections,
including a quick start guide, terminology and reference.
(Bitbake rev: 3089497efc7a1f3f143e151b9d5d024809269b9e)
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
