getting-started, mega-manual: Updated two figures

Had to update the umbrella YP figure and the Poky figure.  The
figures changed on the website so this gets them back in sync.

(From yocto-docs rev: f7f1a689a847ab4a01106eadacfccb4bec6c4b01)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>