update chroot howtos
https://www.torproject.org/download/download-unix.html.en currently links to a heavily dated chroot guide at https://trac.torproject.org/projects/tor/wiki/doc/OpenbsdChrootedTor.
A current and operational document on chroot'g Tor on OpenBSD is located at https://wiki.torbsd.org/doku.php?id=en:openbsd-chroot.
tia