STAMPS_DIR was split out of STAMP recently.
Added some specifics about who is doing what.
(From yocto-docs rev: dafb13f4b3c4cf40292d43ea53fe9150d4dfc0ee)
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>