overview-manual, mega-manual: Updated Package Feeds diagram

The diagram had a typo in it ".ipd" rather than ".ipk".
Fixed and dropped in the figures folder for each manual.

(From yocto-docs rev: d085c285a41bacc15aa78a9f3900f4be7c45fa62)

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