docs: update upload doc (#855)

content/input/upload/index-en-US.md

@@ -870,6 +870,10 @@ class ManulUploadDemo extends React.Component {
 
 `draggable='true'`, you can use the drag and drop function
 
+<Notice type="primary" title="Notice">
+    <div>When the directory is true, because the browser automatically imposes restrictions, it is not allowed to select a single file when clicking upload. When dragging, we think it is more reasonable to allow folders and files to be dragged, so no additional interception processing is performed.</div>
+</Notice>
+
 ```jsx live=true width=48%
 import React from 'react';
 import { Upload } from '@douyinfe/semi-ui';

content/input/upload/index.md

@@ -882,6 +882,9 @@ class ManulUploadDemo extends React.Component {
 ### 拖拽上传
 
 `draggable='true'`，可以使用拖拽功能
+<Notice type="primary" title="注意事项">
+    <div>在directory为true的情况下，因为浏览器自动做了限制，所以点击上传时不允许选单个文件，拖拽时我们认为同时允许文件夹、文件都能拖动更合理，所以不做另外的拦截处理。</div>
+</Notice>
 
 ```jsx live=true width=48%
 import React from 'react';