git-push.txt: clean up force-with-lease wording The help text for the --force-with-lease option to git-push does not parse cleanly. Clean up the wording and syntax to be more sensible. Also remove redundant information in the "--force-with-lease alone" description. Signed-off-by: Phil Hord <hordp@cisco.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>