Documentation: Update README.md to reflect plugin split
Documentation: Update README.md to reflect plugin split

Update README.md to call out how to use priv-net-run.sh and
docker-run.sh scripts post plugin split.

Signed-off-by: Manohar Castelino <f32964ad29a31ea3feb8b48f3bb1748edf23aee2@intel.com>

containernetworking/cni,containernetworking/cni,dcbw/cni,appc/cni,rosenhouse/cni,appc/cni,kad/cni,dcbw/cni,kad/cni,rosenhouse/cni