Add brief documentation of NVDCVE_API_KEY variable, that was added
in 4.2.3, and emphasize that its use results in lower NVD API request
times.
(From yocto-docs rev: 9c7b452441bad2d7c929383d4665dfddb8f7ea72)
Signed-off-by: Noe Galea <ngalea@thegoodpenguin.co.uk>
Reviewed-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Reviewed-by: Andrew Murray <amurray@thegoodpenguin.co.uk>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>