Removed the bit about isolating SDK information. Also removed
the workaround and text regarding the limitation that caused
adding and removing INHERIT += "buildhistory" to re-execute tasks.
Added a few links to some newly documented variables.
(From yocto-docs rev: 7d13bea6d9f0c2bdc9aa58c2933998d6d10ac810)
Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>