Fixes [YOCTO #5888]
Applied some feedback to the variables based on Paul's comments.
Needed a caveat on how you can use these variables.
(From yocto-docs rev: ef8fac4b36089d3162ee16c93866a39bcd31701c)
Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>