added example sriov-net.yaml file in exmaples directory and
updated README.md file showing how to define CRDs with
resourceName annotation for device specific information.
This fix removes 'masterplugin' and 'always_use_default' from
multus config file. default network, defined in
/etc/cni/net.d/*conf should be master and this network should be
used as default from network plumbing working group draft.
