Feature overview extend with both IPv4 and IPv6

[sveeke]

As of now, only one address will be shown. It's better when all IP addresses (in case of internal IP addresses) and both IPv4 and IPv6 (when available and in case of external IP addresses) are shown.

[sveeke]

External IP addresses may be fixed by using ip4.serverbot.net and ip6.serverbot.net with respectively a A record and AAAA record in combination with a simple nginx config like:

location * {
    default_type text/plain;
    return 200 $remote_addr;
}