user-manual: use -o latest.tar.gz to create a gzipped tarball This functionality was introduced by 0e804e09 (archive: provide builtin .tar.gz filter, 2011-07-21) for v1.7.7. Signed-off-by: W. Trevor King <wking@tremily.us> Signed-off-by: Junio C Hamano <gitster@pobox.com>