Commit c85db254 changed the format of the message produced
by "git commit" when creating a commit. This patch updates
the example session in the tutorial to the new format.
It also adds in the missing diffstat summary lines, which
should have been added long ago.
Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>