fix(MonthPicker): 更新模态对话框文档 & 修复月份选择器 bug(#954)

* docs(Modal): 模态对话框文档中没引入组件报错

* fix(MonthPicker): 修复月份选择器，选择下一年时，实际上选择了前一年

Author: nullptr-z

packages/react-modal/README.md

@@ -140,7 +140,7 @@ export default Demo;
 
 ```jsx mdx:preview&bg=#fff
 import React from 'react';
-import { Modal, ButtonGroup, Button, Form, Input, Textarea } from 'uiw';
+import { Modal, ButtonGroup, Button, Form, Input, Textarea, Notify, Row, Col } from 'uiw';
 
 class Demo extends React.Component {
   constructor() {

packages/react-month-picker/src/index.tsx

@@ -106,7 +106,9 @@ export default function MonthPicker(props: MonthPickerProps) {
                 setType(captionType);
               } else {
                 const year = new Date(panelDate).getFullYear();
-                const curPanelDate = new Date(new Date(panelDate).setFullYear(type === 'next' ? year + 1 : year - 1));
+                const curPanelDate = new Date(
+                  new Date(panelDate).setFullYear(captionType === 'next' ? year + 1 : year - 1),
+                );
                 setPanelDate(curPanelDate);
               }
             }}