[docs] Add TileMode.decal images (#85024)

packages/flutter/lib/src/painting/gradient.dart

@@ -412,6 +412,7 @@ class LinearGradient extends Gradient {
   /// For details, see [TileMode].
   ///
   /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_clamp_linear.png)
+  /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_decal_linear.png)
   /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_mirror_linear.png)
   /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_repeated_linear.png)
   final TileMode tileMode;
@@ -639,10 +640,12 @@ class RadialGradient extends Gradient {
   /// For details, see [TileMode].
   ///
   /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_clamp_radial.png)
+  /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_decal_radial.png)
   /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_mirror_radial.png)
   /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_repeated_radial.png)
   ///
   /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_clamp_radialWithFocal.png)
+  /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_decal_radialWithFocal.png)
   /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_mirror_radialWithFocal.png)
   /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_repeated_radialWithFocal.png)
   final TileMode tileMode;
@@ -915,6 +918,7 @@ class SweepGradient extends Gradient {
   /// For details, see [TileMode].
   ///
   /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_clamp_sweep.png)
+  /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_decal_sweep.png)
   /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_mirror_sweep.png)
   /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/tile_mode_repeated_sweep.png)
   final TileMode tileMode;