docs: fix cdn link (#8023)

src/form/README.md

@@ -286,7 +286,7 @@ import { ref } from 'vue';
 
 export default {
   setup() {
-    const value = ref([{ url: 'https://img.yzcdn.cn/vant/leaf.jpg' }]);
+    const value = ref([{ url: 'https://img01.yzcdn.cn/vant/leaf.jpg' }]);
     return { value };
   },
 };

src/form/README.zh-CN.md

@@ -311,7 +311,7 @@ import { ref } from 'vue';
 
 export default {
   setup() {
-    const value = ref([{ url: 'https://img.yzcdn.cn/vant/leaf.jpg' }]);
+    const value = ref([{ url: 'https://img01.yzcdn.cn/vant/leaf.jpg' }]);
     return { value };
   },
 };

src/form/demo/FieldType.vue

@@ -127,7 +127,7 @@ export default {
       radio: '1',
       slider: 50,
       stepper: 1,
-      uploader: [{ url: 'https://img.yzcdn.cn/vant/leaf.jpg' }],
+      uploader: [{ url: 'https://img01.yzcdn.cn/vant/leaf.jpg' }],
       checkbox: false,
       checkboxGroup: [],
       switchChecked: false,

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

@@ -393,7 +393,7 @@ exports[`should render demo and match snapshot 1`] = `
               <div class="van-uploader__wrapper">
                 <div class="van-uploader__preview">
                   <div class="van-image van-uploader__preview-image">
-                    <img src="https://img.yzcdn.cn/vant/leaf.jpg"
+                    <img src="https://img01.yzcdn.cn/vant/leaf.jpg"
                          class="van-image__img"
                          style="object-fit: cover;"
                     >