documentation/dev-manual/figures: Added three figures for sources

(From yocto-docs rev: 956f3d8a35a89caff40531690cdd51fd33b534d2)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>