docs: Document hostport requirements in eni
docs: Document hostport requirements in eni

Strictly speaking this is a general truth for all services, but we don't
have a dedicated section for explaining services and users have begun
reporting specifically in relation to AWS / ENI mode. Put this somewhere
in the docs, we can always move it around to somewhere more generic when
we have a better location for these links to live.

Signed-off-by: Joe Stringer <16a9a54ddf4259952e3c118c763138e83693d7fd@cilium.io>

tklauser/cilium,tklauser/cilium,michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,tgraf/cilium,tgraf/cilium,cilium/cilium,tklauser/cilium,tgraf/cilium,cilium/cilium,tgraf/cilium,tgraf/cilium,cilium/cilium,tgraf/cilium,michi-covalent/cilium,tklauser/cilium,michi-covalent/cilium,tklauser/cilium