Update painting.dart (#22221)

lib/ui/painting.dart

@@ -4540,7 +4540,7 @@ class Canvas extends NativeFieldWrapperClass2 {
   ///       transformList[i * 4 + 0] = 1.0;
   ///       transformList[i * 4 + 1] = 0.0;
   ///       transformList[i * 4 + 2] = sprite.centerX - 5.0;
-  ///       transformList[i * 4 + 2] = sprite.centerY - 5.0;
+  ///       transformList[i * 4 + 3] = sprite.centerY - 5.0;
   ///     }
   ///     Paint paint = Paint();
   ///     canvas.drawAtlas(spriteAtlas, transformList, rectList, null, null, null, paint);
@@ -4600,7 +4600,7 @@ class Canvas extends NativeFieldWrapperClass2 {
   ///       transformList[i * 4 + 0] = transform.scos;
   ///       transformList[i * 4 + 1] = transform.ssin;
   ///       transformList[i * 4 + 2] = transform.tx;
-  ///       transformList[i * 4 + 2] = transform.ty;
+  ///       transformList[i * 4 + 3] = transform.ty;
   ///
   ///       // This example computes the color value directly, but one could also compute
   ///       // an actual Color object and use its Color.value getter for the same result.