watch-array: 代码警告 调整 for 循环写法，移除不需要的 index

pages/component-instance/watch-function/watch-array.uvue

 <template>
   <view>
-    <view v-for="(item, index) in dataList">
+    <view v-for="item in dataList">
       <text class="data-item-text">{{JSON.stringify(item)}}</text>
       <!-- TODO 暂不支持 for UTSJSONObject -->
       <!-- <view v-for="(value, key) in item">
@@ -34,7 +34,7 @@
     },
     watch: {
       dataList: {
-        handler(newValue : Array<UTSJSONObject>) {
+        handler(_ : Array<UTSJSONObject>) {
           this.watchCount++
         },
         deep: true,