message: docs(changelog): 2.2.9
diff: # Changelog
  +### [v2.2.9](https://github.com/youzan/vant/tree/v2.2.9)
  +`2019-10-20`
  +
  +**Features**
  +
  +- Tag: add closeable prop [\#4763](https://github.com/youzan/vant/pull/4763)
  +- Loading: add some less vars [\#4781](https://github.com/youzan/vant/pull/4781)
  +- Progress: add some less vars [\#4790](https://github.com/youzan/vant/pull/4790)
  +- Progress: add track-color prop [\#4789](https://github.com/youzan/vant/pull/4789)
  +- Toast: add @toast-loading-icon-color var [\#4782](https://github.com/youzan/vant/pull/4782)
  +- Picker: add @picker-loading-icon-color var [\#4787](https://github.com/youzan/vant/pull/4787)
  +- ImagePreview: add cover slot [\#4766](https://github.com/youzan/vant/pull/4766)
  +
  +**Bug Fixes**
  +
  +- fix Tag incorrect round radius [\#4762](https://github.com/youzan/vant/pull/4762)
  +- fix Sku emit sku-selected event when reset sku [\#4755](https://github.com/youzan/vant/pull/4755)
  +- fix ImagePreview should not close when click index [\#4764](https://github.com/youzan/vant/pull/4764)
  +- fix AddressEdit choose overseas failure when configuring placeholer [\#4769](https://github.com/youzan/vant/pull/4769)
  +
  +
  ### [v2.2.8](https://github.com/youzan/vant/tree/v2.2.8)
  `2019-10-17`
  