message: docs(changelog): 2.2.7
diff: # Changelog
  +### [v2.2.7](https://github.com/youzan/vant/tree/v2.2.7)
  +`2019-10-11`
  +
  +**Features**
  +
  +- Dialog: add width prop [\#4687](https://github.com/youzan/vant/pull/4687)
  +- Dialog: add overlay-class prop [\#4683](https://github.com/youzan/vant/pull/4683)
  +- Dialog: add overlay-style prop [\#4682](https://github.com/youzan/vant/pull/4682)
  +- Uploader: add file result-type [\#4680](https://github.com/youzan/vant/pull/4680)
  +- TreeSelect: add className option [\#4671](https://github.com/youzan/vant/pull/4671)
  +
  +**Bug Fixes**
  +
  +- fix Dialog avoid text blurry [\#4686](https://github.com/youzan/vant/pull/4686)
  +- fix Stepper can't work when step is small [\#4675](https://github.com/youzan/vant/pull/4675)
  +- fix DatetimePicker should update value when range changed [\#4676](https://github.com/youzan/vant/pull/4676)
  +- fix Field incorrect placeholder color when error and disabled [\#4666](https://github.com/youzan/vant/pull/4666)
  +
  +
  ### [v2.2.6](https://github.com/youzan/vant/tree/v2.2.6)
  `2019-10-08`
  