resolver-conf: add secondary IPv4 and IPv6 for Quad9
I noticed that we provide unsecured variant of Quad9, which means most noticeable no DNSSEC and then no security blocklist, no EDNS Client-Subnet sent. We should let know our users about it.
I am pretty much aware that we don't want to provide DNS server with blocklist, however, some users might be using it and they would like to it. So what about adding a secure variant of Quad9 or at least say in the description that it is Unsecured Quad9?
cc: @kkoci