dev-manual, mega-manual: Updated the Git Workflow figure.

The figure had a wrong box label in the right-bottom box.
I changed it to be like a local Git repository area as it should
be.

(From yocto-docs rev: 2963152decb2d3983180a0af9896e822c865f5cd)

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