Update lxc-checkconfig, to reflect new NFT support.

[skruppy]

After the addition of NFTables in 3.22 (Issue: https://github.com/lxc/lxd/issues/6223 / PR: https://github.com/lxc/lxd/pull/6875), the lxc-checkconfig script should be updated to reflect the new optional kernel configuration requirements (more or less optional, if more Linux distributions drop iptables support).

(... and a big shout-out to everyone involved in bringing nftables support to LXD 🎉 )

[stgraber]

That command comes from the LXC repository instead, moving the issue over there.

[stgraber]

Note that before this really can be marked optional for the LXC repo, we'd need the lxc-net scripts to also be ported to support both iptables and nftables.

[avr1254]

Hi there, just wanted to know more about this issue. Where can I find the changed kernel configuration requirements? Is this issue ready yet, or should I instead look at the lxc-net scripts? Thanks!