Fix docs, our tags don't use a leading 'v'.
Fix docs, our tags don't use a leading 'v'.

cburrows/swift-protobuf,tbkka/swift-protobuf,cburrows/swift-protobuf,cburrows/swift-protobuf,thomasvl/swift-protobuf,cburrows/swift-protobuf,cburrows/swift-protobuf,apple/swift-protobuf,thomasvl/swift-protobuf,tbkka/swift-protobuf,apple/swift-protobuf,tbkka/swift-protobuf,thomasvl/swift-protobuf,thomasvl/swift-protobuf,apple/swift-protobuf,cburrows/swift-protobuf,tbkka/swift-protobuf,tbkka/swift-protobuf,apple/swift-protobuf,cburrows/swift-protobuf,apple/swift-protobuf,tbkka/swift-protobuf,apple/swift-protobuf,thomasvl/swift-protobuf,thomasvl/swift-protobuf,apple/swift-protobuf,tbkka/swift-protobuf,thomasvl/swift-protobuf