Document label-select deployment

[uablrek]

Pre-view at; https://github.com/Nordix/nfproxy/tree/label-select-doc

• I have not tested the nfproxy-label-select.yaml since I don't install nfproxy as a pod myself but start it from a script.

• There is an init-container;

      initContainers:
        - name: filter-forward-policy
          image: docker.io/sbezverk/nfproxy-iptables-fixup:0.0.0
          securityContext:
            privileged: true

Is it still needed when kube-proxy is left intact?

[sbezverk]

It is required in a multinode scenario. I do not have handy a cluster with the kube-proxy to confirm. If in combo scenario filter table has ACCEPT as a policy or its last rule is ACCEPT then, the fix-up is not needed, otherwise nfproxy will not work in a multinode environment.