docs: fix cdn link (#8023)

src/dialog/README.md

@@ -106,7 +106,7 @@ If you need to render vue components within a dialog, you can use dialog compone
 
 ```html
 <van-dialog v-model:show="show" title="Title" show-cancel-button>
-  <img src="https://img.yzcdn.cn/vant/apple-3.jpg" />
+  <img src="https://img01.yzcdn.cn/vant/apple-3.jpg" />
 </van-dialog>
 ```
 

src/dialog/README.zh-CN.md

@@ -139,7 +139,7 @@ export default {
 
 ```html
 <van-dialog v-model:show="show" title="标题" show-cancel-button>
-  <img src="https://img.yzcdn.cn/vant/apple-3.jpg" />
+  <img src="https://img01.yzcdn.cn/vant/apple-3.jpg" />
 </van-dialog>
 ```
 

src/dialog/demo/index.vue

@@ -108,7 +108,7 @@ export default {
     return {
       t,
       show,
-      image: 'https://img.yzcdn.cn/vant/apple-3.jpg',
+      image: 'https://img01.yzcdn.cn/vant/apple-3.jpg',
       onClickAlert,
       onClickAlert2,
       onClickRound,

src/dialog/test/__snapshots__/demo.spec.js.snap

@@ -104,7 +104,7 @@ exports[`should render demo and match snapshot 1`] = `
         Title
       </div>
       <div class="van-dialog__content">
-        <img src="https://img.yzcdn.cn/vant/apple-3.jpg">
+        <img src="https://img01.yzcdn.cn/vant/apple-3.jpg">
       </div>
       <div class="van-hairline--top van-dialog__footer">
         <button type="button"