Description of problem:

Warn users that it isn't supported in the docs.

Actual behavior:
As explained in this Jira when a proxy is created using an IPv6 as URL, it does not work properly.

Expected behavior:

Insert as example url about Sat 6.14,
Read a sentence from Documentation link https://access.redhat.com/documentation/en-us/red_hat_satellite/6.14/html/installing_satellite_server_in_a_connected_network_environment/preparing-environment-for-installation-in-ipv6-network_satellite