fix documentation for git-commit --no-verify

fix documentation for git-commit --no-verify

Despite what the documentation claims, git-commit does not check commit
for suspicious lines: all hooks are disabled by default,
and the pre-comit hook could be changed to do something else.

Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Junio C Hamano <junkio@cox.net>