feat(Uploader): add preview-cover slot (#6707)

* feat(Uploader): add preview-cover slot

* docs: upd

* fix: case name

src/uploader/README.md

@@ -43,12 +43,6 @@ export default {
 };
 ```
 
-### Disabled
-
-```html
-<van-uploader disabled />
-```
-
 ### Upload Status
 
 ```html
@@ -106,32 +100,54 @@ export default {
 ### Max Size
 
 ```html
-<van-uploader
-  multiple
-  :max-count="5"
-  :max-size="3 * 1024 * 1024"
-  @oversize="onOversize"
-/>
+<van-uploader multiple :max-size="500 * 1024" @oversize="onOversize" />
 ```
 
 ```js
+import { Toast } from 'vant';
+
 export default {
   methods: {
     onOversize(file) {
       console.log(file);
+      Toast('File size cannot exceed 500kb);
     },
   },
 };
 ```
 
-### Upload Style
+### Custom Upload Area
 
 ```html
 <van-uploader>
-  <van-button icon="photo" type="primary">Upload Image</van-button>
+  <van-button icon="plus" type="primary">Upload Image</van-button>
 </van-uploader>
 ```
 
+### Preview Cover
+
+```html
+<van-uploader v-model="fileList">
+  <template #preview-cover="{ file }">
+    <div class="preview-cover van-ellipsis">{{ file.name }}</div>
+  </template>
+</van-uploader>
+
+<style>
+  .preview-cover {
+    position: absolute;
+    box-sizing: border-box;
+    bottom: 0;
+    width: 100%;
+    padding: 4px;
+    color: #fff;
+    font-size: 12px;
+    text-align: center;
+    background: rgba(0, 0, 0, 0.3);
+  }
+</style>
+```
+
 ### Before Read
 
 ```html
@@ -167,12 +183,21 @@ export default {
 };
 ```
 
+### Disable Uploader
+
+Use `disabled` prop to disable uploader.
+
+```html
+<van-uploader disabled />
+```
+
 ## API
 
 ### Props
 
 | Attribute | Description | Type | Default |
 | --- | --- | --- | --- |
+| v-model (fileList) | List of uploaded files | _FileListItem[]_ | - |
 | accept | Accepted [file type](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/file#Unique_file_type_specifiers) | _string_ | `image/*` |
 | name `v2.0.3` | Input name | _number \| string_ | - |
 | preview-size | Size of preview image | _number \| string_ | `80px` |
@@ -205,9 +230,10 @@ export default {
 
 ### Slots
 
-| Name    | Description |
-| ------- | ----------- |
-| default | Custom icon |
+| Name | Description | SlotProps |
+| --- | --- | --- |
+| default | Custom icon | - |
+| preview-cover `v2.9.1` | Custom content that covers the image preview | `item: FileListItem` |
 
 ### Parematers of before-read、after-read、before-delete