VirtualAddrNetworkIPv6 manpage entry correction

This section of the manual needs a minor revision.

       VirtualAddrNetworkIPv6 [Address]/bits
           When Tor needs to assign a virtual (unused) address because of a
           MAPADDRESS command from the controller or the AutomapHostsOnResolve
           feature, Tor picks an unassigned address from this range.
           (Defaults: 127.192.0.0/10 and [FE80::]/10 respectively.)

           When providing proxy server service to a network of computers using
           a tool like dns-proxy-tor, change the IPv4 network to
           "10.192.0.0/10" or "172.16.0.0/12" and change the IPv6 network to
           "[FC00]/7".

[FC00]/7 should read [FC00::]/7

See Error configuring tor as transparent proxy with IPv6 on the Tor Stack Exchange.