util: NetworkMonitor: macOS version of fine-grained signals on interface state changes

Change-Id: I6da12356baa0038d08ff256d0d3ff726023d804b
Refs: #3817
diff --git a/src/util/network-monitor.hpp b/src/util/network-monitor.hpp
index 59b9dc7..629a80e 100644
--- a/src/util/network-monitor.hpp
+++ b/src/util/network-monitor.hpp
@@ -49,11 +49,9 @@
  *
  * @note Implementation of this class is platform dependent and not all supported platforms
  *       are supported:
- *       - OS X: CFNotificationCenterAddObserver (incomplete)
+ *       - OS X: SystemConfiguration and CFNotificationCenterAddObserver notifications (no
+ *         notification on MTU change)
  *       - Linux: rtnetlink notifications
- *
- * @todo macOS implementation needs to be updated to emit the new signals and keep track of
- *       interfaces (links) and addresses
  */
 class NetworkMonitor : noncopyable
 {