Improve Pktgen documentation with example of NF processing real packets

[twood02]

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Documentation, Integration Strategy
Currently we do not have any good documentation on running an NF to process real network traffic (I think all of our examples just use speed tester). We should add an example of running either the bridge NF or basic monitor to show how to forward/mirror packets back to pktgen.

I suggest improving this wiki article: https://github.com/sdnfv/openNetVM/wiki/Packet-generation-using-Pktgen