Improve visualization for subnets and nameservers

[remyleone]

When I got several nameservers and a subnet inside my IPv6 prefix, the rendering could be improved:

$ scw dedibox ipv6-block get
ID                          3622
Address                     2001:bc8:3010::
Duid                        00:03:00:01:2e:b3:0a:82:7d:57
Nameservers.0               example.com
Nameservers.1               foo.com
Nameservers.2               bar.com
Nameservers.3               foobar.com
Nameservers.4               barfoo.com
Cidr                        48
Subnets.0.ID                46572
Subnets.0.Address           2001:bc8:3010:100::
Subnets.0.Duid              00:03:00:01:9b:be:69:36:41:10
Subnets.0.Cidr              56
Subnets.0.DelegationStatus  unknown_status
DelegationStatus            updating