[Doc] new theme

packages/stepper/en-US.md

@@ -1,15 +1,16 @@
-## Stepper
+# Stepper
 
 ### Install
+
 ``` javascript
 import { Stepper } from 'vant';
 
 Vue.use(Stepper);
 ```
 
-### Usage
+## Usage
 
-#### Basic Usage
+### Basic Usage
 
 ```html
 <van-stepper v-model="value" />
@@ -25,13 +26,13 @@ export default {
 }
 ```
 
-#### Disabled
+### Disabled
 
 ```html
 <van-stepper v-model="value" disabled />
 ```
 
-#### Async Change
+### Async Change
 
 ```html
 <van-stepper
@@ -65,7 +66,7 @@ export default {
 }
 ```
 
-#### Advanced Usage
+### Advanced Usage
 
 ```html
 <van-stepper
@@ -78,6 +79,8 @@ export default {
 />
 ```
 
+## API
+
 ### Props
 
 | Attribute | Description | Type | Default |