docs(List): add PullRefresh demo (#5579)

src/list/README.zh-CN.md

@@ -39,14 +39,15 @@ export default {
       finished: false
     };
   },
-
   methods: {
     onLoad() {
       // 异步更新数据
+      // setTimeout 仅做示例，真实场景中一般为 ajax 请求
       setTimeout(() => {
         for (let i = 0; i < 10; i++) {
           this.list.push(this.list.length + 1);
         }
+
         // 加载状态结束
         this.loading = false;
 
@@ -54,7 +55,7 @@ export default {
         if (this.list.length >= 40) {
           this.finished = true;
         }
-      }, 500);
+      }, 1000);
     }
   }
 }
@@ -84,7 +85,6 @@ export default {
       loading: false
     };
   },
-
   methods: {
     onLoad() {
       fetchSomeThing().catch(() => {
@@ -95,6 +95,64 @@ export default {
 }
 ```
 
+### 下拉刷新
+
+List 组件可以与 [PullRefresh](#/zh-CN/pull-refresh) 组件结合使用，实现下拉刷新的效果
+
+```html
+<van-pull-refresh v-model="refreshing" @refresh="onRefresh">
+  <van-list
+    v-model="loading"
+    :finished="finished"
+    finished-text="没有更多了"
+    @load="onLoad"
+  >
+    <van-cell v-for="item in list" :key="item" :title="item" />
+  </van-list>
+</van-pull-refresh>
+```
+
+```js
+export default {
+  data() {
+    return {
+      list: [],
+      loading: false,
+      finished: false,
+      refreshing: false
+    };
+  },
+  methods: {
+    onLoad() {
+      setTimeout(() => {
+        if (this.refreshing) {
+          this.list = [];
+          this.refreshing = false;
+        }
+
+        for (let i = 0; i < 10; i++) {
+          this.list.push(this.list.length + 1);
+        }
+        this.loading = false;
+
+        if (this.list.length >= 40) {
+          this.finished = true;
+        }
+      }, 1000);
+    },
+    onRefresh() {
+      // 清空列表数据
+      this.finished = false;
+
+      // 重新加载数据
+      // 将 loading 设置为 true，表示处于加载状态
+      this.loading = true;
+      this.onLoad();
+    }
+  }
+}
+```
+
 ## API
 
 ### Props