refactor: modify upload dragger name from 'ADragger' to 'AUploadDragger'

Author: tangjinzhou

components/upload/Dragger.jsx

@@ -3,7 +3,7 @@ import Upload from './Upload'
 import { UploadProps } from './interface'
 
 export default {
-  name: 'ADragger',
+  name: 'AUploadDragger',
   props: UploadProps,
   render () {
     const props = getOptionProps(this)

components/upload/demo/drag.md

@@ -11,13 +11,13 @@ Classic mode. File selection dialog pops up when upload button is clicked.
 
 ```html
 <template>
-  <a-dragger name="file" :multiple="true" action="//jsonplaceholder.typicode.com/posts/" @change="handleChange">
+  <a-upload-dragger name="file" :multiple="true" action="//jsonplaceholder.typicode.com/posts/" @change="handleChange">
     <p class="ant-upload-drag-icon">
       <a-icon type="inbox" />
     </p>
     <p class="ant-upload-text">Click or drag file to this area to upload</p>
     <p class="ant-upload-hint">Support for a single or bulk upload. Strictly prohibit from uploading company data or other band files</p>
-  </a-dragger>
+  </a-upload-dragger>
 </template>
 <script>
 export default {