Update progress_indicator.dart to indicate the adaptive option is for…

… both macOS and iOS (#145246)

Since we are using The `CupertinoScrollBar` for both macOS and iOS, it's a good idea to update the description of the `adaptive` function to indicate it will be used for macOS and iOS

*Update progress_indicator.dart to indicate the adaptive option is for both macOS and iOS.*

![image](https://github.com/flutter/flutter/assets/73608287/51c21a43-ce64-4253-aff7-1854a7366eea)

packages/flutter/lib/src/material/progress_indicator.dart

@@ -566,11 +566,11 @@ class CircularProgressIndicator extends ProgressIndicator {
   }) : _indicatorType = _ActivityIndicatorType.material;
 
   /// Creates an adaptive progress indicator that is a
-  /// [CupertinoActivityIndicator] in iOS and [CircularProgressIndicator] in
-  /// material theme/non-iOS.
+  /// [CupertinoActivityIndicator] in [TargetPlatform.iOS] & [TargetPlatform.macOS] and [CircularProgressIndicator] in
+  /// material theme/non-Apple platforms.
   ///
   /// The [value], [valueColor], [strokeWidth], [semanticsLabel], and
-  /// [semanticsValue] will be ignored in iOS.
+  /// [semanticsValue] will be ignored in iOS & macOS.
   ///
   /// {@macro flutter.material.ProgressIndicator.ProgressIndicator}
   const CircularProgressIndicator.adaptive({