docs: collapse-translation (#2216)

components/collapse/demo/accordion.md

@@ -1,10 +1,18 @@
 ---
 order: 1
-title: 手风琴
+title: 
+  zh-CN: 手风琴
+  en-US: Accordion
 ---
 
+## zh-CN
+
 手风琴，每次只打开一个tab。默认打开第一个。
 
+## en-US
+
+Accordion mode, only one panel can be expanded at a time. The first panel will be expanded by default.
+
 ````jsx
 import { Collapse } from 'antd';
 const Panel = Collapse.Panel;

components/collapse/demo/basic.md

@@ -1,10 +1,18 @@
 ---
 order: 0
-title: 折叠面板
+title: 
+  zh-CN: 折叠面板
+  en-US: Collapse
 ---
 
+## zh-CN
+
 可以同时展开多个面板，这个例子默认展开了第一个。
 
+## en-US
+
+More than one panel can be expanded at a time, the first panel is initialized to be active in this case.
+
 ````jsx
 import { Collapse } from 'antd';
 const Panel = Collapse.Panel;

components/collapse/demo/mix.md

@@ -1,10 +1,18 @@
 ---
 order: 2
-title: 面板嵌套
+title: 
+  zh-CN: 面板嵌套
+  en-US: Nested panel
 ---
 
+## zh-CN
+
 手风琴嵌套折叠面板。
 
+## en-US
+
+`Collapse` is nested inside the `Accordion`.
+
 ````jsx
 import { Collapse } from 'antd';
 const Panel = Collapse.Panel;

components/collapse/index.en-US.md

@@ -0,0 +1,30 @@
+---
+category: Components
+type: Views
+title: Collapse
+---
+
+A content area which can be collapsed and expanded.
+
+## When to use
+
+- Can be used to group or hide complex regions to keep the page clean.
+- `Accordion` is a special kind of `Collapse`, which allows only one panel to be expanded at a time.
+
+## API
+
+### Collapse
+
+| Property     | Description           | Type     | Default       |
+|----------|----------------|----------|--------------|
+| activeKey    | key of the active panel | Array or String   | No default value. In `accordion` mode, it's the key of the first panel.  |
+| defaultActiveKey    | key of the initialized active panel | String   | - |
+| onChange | a callback function, which can be executed when you switch the panels | Function   |  -  |
+
+### Collapse.Panel
+
+| Property     | Description           | Type     | Default       |
+|----------|----------------|----------|--------------|
+| key    | corresponds to the `activeKey` | String   |  -  |
+| header    | title of the panel | React.Element or String   | - |
+

components/collapse/index.zh-CN.md

@@ -1,8 +1,8 @@
 ---
 category: Components
-chinese: 折叠面板
 type: Views
-english: Collapse
+title: Collapse
+subtitle: 折叠面板
 ---
 
 可以折叠/展开的内容区域。