Update link to Tor directory specifications
The link to Tor directory specifications on https://weather.torproject.org/notification_info/ points to https://svn.torproject.org/svn/tor/trunk/doc/spec/dir-spec.txt.
The link to Tor directory specifications on https://weather.torproject.org/notification_info/ points to https://svn.torproject.org/svn/tor/trunk/doc/spec/dir-spec.txt.