fixup multicast documentation
fixup multicast documentation

Change-Id: Icde82689578c9148a58a0a36cc4b07d316d7fdfa

clive-jevons/joynr,clive-jevons/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,bmwcarit/joynr,clive-jevons/joynr,bmwcarit/joynr,clive-jevons/joynr,clive-jevons/joynr,bmwcarit/joynr,bmwcarit/joynr,clive-jevons/joynr