docs(harmonyos): Update StackLayout flex properties

Update the flex properties of the StackLayout in order to align its items to the start and justify the space between them. This change will improve the layout of the components displayed in the StackLayout.

Author: phodal

exts/ext-harmonyos/src/main/kotlin/cc/unitmesh/harmonyos/actions/auto/ArkUiLayoutType.kt

@@ -87,7 +87,7 @@ enum class ArkUiLayoutType(val description: String, val example: String) {
     StackLayout(
         "层叠布局（StackLayout）用于在屏幕上预留一块区域来显示组件中的元素，提供元素可以重叠的布局。",
         "Stack({ alignContent: Alignment.Bottom }) {\n" +
-                "    Flex({ wrap: FlexWrap.Wrap }) {\n" +
+                "    Flex({ justifyContent: FlexAlign.SpaceBetween, wrap: FlexWrap.Wrap, alignContent: FlexAlign.Start }) {\n" +
                 "      ForEach(this.arr, (item) => {\n" +
                 "        Text(item)\n" +
                 "          .width(100)\n" +