Update overload article
0.4.6.9 and 0.4.7.3-alpha took potential DNS overload out of the overload criteria (see: tpo/network-health/team#139 (closed) and https://lists.torproject.org/pipermail/tor-relays/2021-December/020064.html for details), we should update our support article both to take
- the new reality starting with 0.4.6.9/0.4.7.3-alpha
- and the old reality (relays stuck on Tor 0.4.6.x < 0.4.6.9/0.4.7.x < 0.4.7.3-alpha)
into account.