[Tor-BSD] buildbot for BSD Tor relays

[George Rosamond]

For those who weren't aware, a list member is hosting a BSD buildbot for
BSD Tor relays at https://buildbot.pixelminers.net

At this point, only (my) two public relays are listed, but it would be
useful for the Tor Project to have more involved.  We only heard it was
down when someone on #tor-dev noted it was down, which confirms its
getting some usage.

The instructions are simple enough at the above URL.

g