Add captive portal entry for dual stack setups (#1835)

For users with a dual stack set up at home (IPv4+native IPv6), Windows 21H1 will report that there is no Internet connection if this entry is missing from their captive portals file.

Signed-off-by: Aaron <admin@datahoarder.dev>

Author: Aaron

dnscrypt-proxy/example-captive-portals.txt

@@ -19,4 +19,5 @@ connectivitycheck.android.com   64.233.162.100, 64.233.162.101, 64.233.162.102,
 www.msftncsi.com                2.16.106.89, 2.16.106.91, 23.0.175.137, 23.0.175.146, 23.192.47.155, 23.192.47.203, 23.199.63.160, 23.199.63.184, 23.199.63.208, 23.204.146.160, 23.204.146.163, 23.46.238.243, 23.46.239.24, 23.48.39.16, 23.48.39.48, 23.55.38.139, 23.55.38.146, 23.59.190.185, 23.59.190.195
 dns.msftncsi.com                131.107.255.255, fd3e:4f5a:5b81::1
 www.msftconnecttest.com         13.107.4.52
+ipv6.msftconnecttest.com        2a01:111:2003::52
 ipv4only.arpa                   192.0.0.170, 192.0.0.171