[j-nsp] 6PE without family inet6 labeled-unicast

[Pavel Lunin]

> Looks like it's all documented except next-hop conversion...
>

It's RFC4798 which prescribes to do so. Juniper/Cisco docs mention this
behavior briefly (google://bgp ipv4 ipv6 mapped ffff) but they consider it
part of BGP itself, not specific to implementation / configuration, so not
their job to document ;) But I agree, it's a bit confusing, they could've
done better.