Generating SPDX is enabled by default in poky but
it can take a lot of build time resources so document
how to disable it.
(From yocto-docs rev: bcd58b7a9455fbb0ea5944089d663e327f0eb38f)
Signed-off-by: Mikko Rapeli <mikko.rapeli@linaro.org>
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>