The "git pull" documentation has examples which follow an outdated
style. Update the examples to use "git merge" where appropriate and
move the examples to the corresponding manpages.
Furthermore,
- show that pull is equivalent to fetch and merge, which is still a
frequently asked question,
- explain the default fetch refspec.
Signed-off-by: Clemens Buchacher <drizzd@aon.at> Signed-off-by: Junio C Hamano <gitster@pobox.com>