[Android] Update SystemUiMode and setSystemChromeEnabledSystemUIMode docs to note targeting Android 15+ change (flutter#153466)

Updates `SystemUiMode` and `setSystemChromeEnabledSystemUIMode` documentation to reflect that edge-to-edge mode is used by default if the Flutter app targets Android 15.

Part of flutter#150367 and framework counterpart to flutter/engine#54560.

Author: camsim99

packages/flutter/lib/src/services/system_chrome.dart

@@ -92,12 +92,21 @@ enum SystemUiOverlay {
 /// These modes mimic Android-specific display setups.
 ///
 /// Used by [SystemChrome.setEnabledSystemUIMode].
+///
+/// Flutter apps use [SystemUiMode.edgeToEdge] by default and setting any
+/// of the other [SystemUiMode]s will NOT work unless you perform the migration
+/// detailed in
+/// https://docs.flutter.dev/release/breaking-changes/default-systemuimode-edge-to-edge.
 enum SystemUiMode {
   /// Fullscreen display with status and navigation bars presentable by tapping
   /// anywhere on the display.
   ///
-  /// Available starting at SDK 16 or Android J. Earlier versions of Android
-  /// will not be affected by this setting.
+  /// Available starting at Android SDK 4.1 (API 16). Earlier versions of Android
+  /// will not be affected by this setting. However, if your app targets Android
+  /// SDK 15 (API 35) or later (Flutter does this by default), then you must
+  /// migrate using the instructions in
+  /// https://docs.flutter.dev/release/breaking-changes/default-systemuimode-edge-to-edge
+  /// to use this mode.
   ///
   /// For applications running on iOS, the status bar and home indicator will be
   /// hidden for a similar fullscreen experience.
@@ -114,8 +123,12 @@ enum SystemUiMode {
   /// Fullscreen display with status and navigation bars presentable through a
   /// swipe gesture at the edges of the display.
   ///
-  /// Available starting at SDK 19 or Android K. Earlier versions of Android
-  /// will not be affected by this setting.
+  /// Available starting at Android SDK 4.4 (API 19). Earlier versions of
+  /// Android will not be affected by this setting. However, if your app targets
+  /// Android SDK 15 (API 35) or later (Flutter does this by default), then you
+  /// must migrate using the instructions in
+  /// https://docs.flutter.dev/release/breaking-changes/default-systemuimode-edge-to-edge
+  /// to use this mode.
   ///
   /// For applications running on iOS, the status bar and home indicator will be
   /// hidden for a similar fullscreen experience.
@@ -133,8 +146,12 @@ enum SystemUiMode {
   /// Fullscreen display with status and navigation bars presentable through a
   /// swipe gesture at the edges of the display.
   ///
-  /// Available starting at SDK 19 or Android K. Earlier versions of Android
-  /// will not be affected by this setting.
+  /// Available starting at Android SDK 4.4 (API 19). Earlier versions of
+  /// Android will not be affected by this setting. However, if your app targets
+  /// Android SDK 15 (API 35) or later (Flutter does this by default), then you
+  /// must migrate using the instructions in
+  /// https://docs.flutter.dev/release/breaking-changes/default-systemuimode-edge-to-edge
+  /// to use this mode.
   ///
   /// For applications running on iOS, the status bar and home indicator will be
   /// hidden for a similar fullscreen experience.
@@ -151,9 +168,13 @@ enum SystemUiMode {
   /// Fullscreen display with status and navigation elements rendered over the
   /// application.
   ///
-  /// Available starting at SDK 29 or Android 10. Earlier versions of Android
+  /// Available starting at Android SDK 10 (API 29). Earlier versions of Android
   /// will not be affected by this setting.
   ///
+  /// If your app targets Android SDK 15 (API 35) or later (Flutter does this by
+  /// default), then this mode is used by default on Android. This mode is also
+  /// used by default on iOS.
+  ///
   /// For applications running on iOS, the status bar and home indicator will be
   /// visible.
   ///
@@ -181,6 +202,11 @@ enum SystemUiMode {
   ///
   /// Omitting both overlays will result in the same configuration as
   /// [SystemUiMode.leanBack].
+  ///
+  /// If your app targets Android SDK 15 (API 35) or later, then you must
+  /// migrate using the instructions in
+  /// https://docs.flutter.dev/release/breaking-changes/default-systemuimode-edge-to-edge
+  /// to use this mode.
   manual,
 }
 
@@ -502,6 +528,12 @@ abstract final class SystemChrome {
   /// is true, the application is not fullscreen. See
   /// [SystemChrome.setSystemUIChangeCallback] to respond to these changes in a
   /// fullscreen application.
+  ///
+  /// If your app targets Android SDK 15 (API 35) or later (Flutter does this by
+  /// default), then your Flutter app uses [SystemUiMode.edgeToEdge] by default
+  /// on Android and setting any of the other [SystemUiMode]s will NOT work
+  /// unless you perform the migration detailed in
+  /// https://docs.flutter.dev/release/breaking-changes/default-systemuimode-edge-to-edge.
   static Future<void> setEnabledSystemUIMode(SystemUiMode mode, { List<SystemUiOverlay>? overlays }) async {
     if (mode != SystemUiMode.manual) {
       await SystemChannels.platform.invokeMethod<void>(