document the state of use of iptables 1.8

[murali-reddy]

What happened?

kube-router added support for iptables 1.8 version. iptables 1.8 version on wards it has suppor for both nftables and iptables. More details can be found in this document

https://developers.redhat.com/blog/2020/08/18/iptables-the-two-variants-and-their-relationship-with-nftables#the_iptables_rules_appear_in_the_nftables_rule_listing

kube-router already added support for iptables-wrapper which keeps iptables mode compatibility with the host. So you can use kube-router with both iptables-legacy and iptables-nft. However kube-router does not support nftables and no plans to support it as well.

What did you expect to happen?

document current stance of the project with respect to use of nftables and usage of iptables 1.8