Fixes [YOCTO #5408]
As part of the fix for this bug, I have added a description of this
variable to the glossary.
(From yocto-docs rev: ad988c82b364bb0c629bcb2ce04f99e0e371622e)
Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>