Add yang-version 1.1 example for maven plugin to doc

I could not find a single example YANG module in https://docs.opendaylight.org or on https://wiki.opendaylight.org/view/YANG_Tools that is marked with "yang-version 1.1;"  Please add a new example to show how that works and the configuration operations (if any) that are required for generating Java code from a 1.1 module using the maven plugin.