fix(image-preview)：fix image-preview README、supplement teleport (#11429)

Co-authored-by: xuwenqiang <xuwenqiang@kanzhun.com>

packages/vant/src/image-preview/ImagePreview.tsx

@@ -8,6 +8,7 @@ import {
   type PropType,
   type CSSProperties,
   type ExtractPropTypes,
+  type TeleportProps,
 } from 'vue';
 
 // Utils
@@ -46,6 +47,7 @@ const popupProps = [
   'transition',
   'overlayStyle',
   'closeOnPopstate',
+  'teleport'
 ] as const;
 
 export const imagePreviewProps = {
@@ -68,6 +70,7 @@ export const imagePreviewProps = {
   showIndicators: Boolean,
   closeOnPopstate: truthProp,
   closeIconPosition: makeStringProp<PopupCloseIconPosition>('top-right'),
+  teleport: [String, Object] as PropType<TeleportProps['to']>,
 };
 
 export type ImagePreviewProps = ExtractPropTypes<typeof imagePreviewProps>;

packages/vant/src/image-preview/README.md

@@ -109,7 +109,7 @@ setTimeout(() => {
 
 ```html
 <van-image-preview v-model:show="show" :images="images" @change="onChange">
-  <template v-slot:index>Page: {{ index }}</template>
+  <template v-slot:index>Page: {{ index + 1 }}</template>
 </van-image-preview>
 ```
 

packages/vant/src/image-preview/README.zh-CN.md

@@ -120,7 +120,7 @@ setTimeout(() => {
 
 ```html
 <van-image-preview v-model:show="show" :images="images" @change="onChange">
-  <template v-slot:index>第{{ index }}页</template>
+  <template v-slot:index>第{{ index + 1  }}页</template>
 </van-image-preview>
 ```