Fix material reference in CupertinoPicker doc (#25584)

packages/flutter/lib/src/cupertino/picker.dart

diff --git a/packages/flutter/lib/src/cupertino/picker.dart b/packages/flutter/lib/src/cupertino/picker.dart
index 99fa470..0975de9 100644
--- a/packages/flutter/lib/src/cupertino/picker.dart
+++ b/packages/flutter/lib/src/cupertino/picker.dart
@@ -23,7 +23,7 @@
 /// Displays its children widgets on a wheel for selection and
 /// calls back when the currently selected item changes.
 ///
-/// Can be used with [showModalBottomSheet] to display the picker modally at the
+/// Can be used with [showCupertinoModalPopup] to display the picker modally at the
 /// bottom of the screen.
 ///
 /// See also: