Added more explanatory text with appropriate links. Included a
link to the new "how-to" section in the dev-manual.
(From yocto-docs rev: 929185c387d9f745857786086750bf68cb4c7b9b)
Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>