mega-manual: New PNG file for mega-manual title page.

(From yocto-docs rev: e3d8af0c6cd88e76f7cf2bcff82e1fffd7a46589)

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