[tor-mirrors] Update to rsync cronjob on running a mirror directions

Thanks to creep.im mirror admin, he/she found a mistake in the directions: The correct rsync command is: rsync -av --delete rsync://rsync.torproject.org/website-mirror tor-mirror/ The updated page with these instructions is live at https://www.torproject.org/docs/running-a-mirror.html.en Sorry for any confusion. -- Andrew http://tpo.is/contact pgp 0x6B4D6475