Clarify that "queue" is not a DispatchQueue
Clarify that "queue" is not a DispatchQueue

Co-authored-by: Konrad `ktoso` Malawski <aaec9560ae3ffb2718ed536266060ba3fb575dcb@apple.com>
apple/swift-evolution,abertelrud/swift-evolution,abertelrud/swift-evolution,apple/swift-evolution,natecook1000/swift-evolution,natecook1000/swift-evolution