Update API doc for scroll_configuration's dragDevices

Update API doc for scroll_configuration's dragDevices
diff --git a/packages/flutter/lib/src/widgets/scroll_configuration.dart b/packages/flutter/lib/src/widgets/scroll_configuration.dart
index ddff43e..2e089f5 100644
--- a/packages/flutter/lib/src/widgets/scroll_configuration.dart
+++ b/packages/flutter/lib/src/widgets/scroll_configuration.dart
@@ -112,10 +112,11 @@
 
   /// The device kinds that the scrollable will accept drag gestures from.
   ///
-  /// By default only [PointerDeviceKind.touch], [PointerDeviceKind.stylus], and
-  /// [PointerDeviceKind.invertedStylus] are configured to create drag gestures.
-  /// Enabling this for [PointerDeviceKind.mouse] will make it difficult or
-  /// impossible to select text in scrollable containers and is not recommended.
+  /// By default only [PointerDeviceKind.touch], [PointerDeviceKind.stylus],
+  /// [PointerDeviceKind.invertedStylus] and [PointerDeviceKind.trackpad] are
+  /// configured to create drag gestures. Enabling this for
+  /// [PointerDeviceKind.mouse] will make it difficult or impossible to select
+  /// text in scrollable containers and is not recommended.
   Set<PointerDeviceKind> get dragDevices => _kTouchLikeDeviceTypes;
 
   /// {@macro flutter.gestures.monodrag.DragGestureRecognizer.multitouchDragStrategy}