message: docs(changelog): 2.1.6
diff: # Changelog
  +### [v2.1.6](https://github.com/youzan/vant/tree/v2.1.6)
  +`2019-08-26`
  +
  +**Improvements**
  +
  +- Tag: add warning type [\#4232](https://github.com/youzan/vant/pull/4232)
  +- Image: add radius prop [\#4230](https://github.com/youzan/vant/pull/4230)
  +- Notify: add type prop [\#4237](https://github.com/youzan/vant/pull/4237)
  +- CellGroup: add title slot [\#4227](https://github.com/youzan/vant/pull/4227)
  +- Sku: initialSku can be set dynamically [\#4214](https://github.com/youzan/vant/pull/4214)
  +- Sku: can preview images of non-first level sku [\#4236](https://github.com/youzan/vant/pull/4236)
  +- Locale: add Spanish translation [\#4235](https://github.com/youzan/vant/pull/4235)
  +
  +**Bug Fixes**
  +
  +- fix Tabbar incorrect active style in route mode [\#4229](https://github.com/youzan/vant/pull/4229)
  +- fix NumberKeyboard incorrect sidebar position when has title [\#4228](https://github.com/youzan/vant/pull/4228)
  +- fix IndexBar the problem of rolling out parent boundaries when sticky bottom [\#4218](https://github.com/youzan/vant/pull/4218)
  +
  +
  ### [v2.1.5](https://github.com/youzan/vant/tree/v2.1.5)
  `2019-08-23`
  