[new feature] #734 swipe组件支持垂直滚动 (#938)

docs/markdown/en-US/swipe.md

@@ -66,6 +66,17 @@ export default {
 }
 ```
 
+#### Vertical Scrolling
+
+```html
+<van-swipe :autoplay="3000" vertical>
+  <van-swipe-item>1</van-swipe-item>
+  <van-swipe-item>2</van-swipe-item>
+  <van-swipe-item>3</van-swipe-item>
+  <van-swipe-item>4</van-swipe-item>
+</van-swipe>
+```
+
 ### API
 
 | Attribute | Description | Type | Default | Accepted Values |
@@ -75,6 +86,7 @@ export default {
 | loop | Whether to enable loop | `Boolean` | `true` | - |
 | show-indicators | Whether to show indocators | `Boolean` | `true` | - |
 | initial-swipe | Index of initial swipe, start from 0 | `Number` | `0` | - |
+| vertical | Vertical Scrolling | `Boolean` | `false` | - |
 
 ### Event