Update dart doc for `Service.getIsolateId`
diff --git a/sdk/lib/developer/service.dart b/sdk/lib/developer/service.dart
index ba453c3..9854a48 100644
--- a/sdk/lib/developer/service.dart
+++ b/sdk/lib/developer/service.dart
@@ -103,6 +103,9 @@
   ///
   /// Returns null if the running Dart environment does not support the service
   /// protocol.
+  ///
+  /// To get the isolate id of the current isolate, pass [Isolate.current] as
+  /// the [isolate] parameter.
   @Since('3.2')
   static String? getIsolateId(Isolate isolate) {
     // TODO: When NNBD is complete, delete the following line.