docs(category): update demo code

src/packages/__VUE/category/doc.taro.md

@@ -47,7 +47,7 @@ export default {
     });
 
     const change = (index: any) => {
-      data.categoryChild = [].concat(data.categoryInfo.category[index].children as any);
+      data.categoryChild = [].concat(data.category.category[index].children as any);
     };
     const onChange =()=>{
         console.log("当前分类数据");
@@ -94,7 +94,7 @@ export default {
     });
 
     const changeText = (index: any) => {
-      data.categoryChild = [].concat(data.categoryInfo.category[index].children as any);
+      data.categoryChild = [].concat(data.category.category[index].children as any);
     };
 
     const onChange =()=>{