message: docs(ImagePreview): fix swipeTo method
diff: @@ -159,6 +159,13 @@ export default {
  | closed `v2.5.6` | Emitted when ImagePreview is closed | - |
  | change | Emitted when current image changed | index: index of current image |
  | scale `v2.5.0` | Emitted when scaling current image | { index: index of current image, scale: scale of current image} |
  +
  +### Methods
  +
  +Use [ref](https://vuejs.org/v2/api/#ref) to get ImagePreview instance and call instance methods.
  +
  +| Name | Description | Attribute | Return value |
  +| --- | --- | --- | --- |
  | swipeTo `2.9.0` | Swipe to target index | index: target index, options: Options | - |
  ### Slots
  