Update CHANGELOG.md

Author: rpkyle

CHANGELOG.md

@@ -5,6 +5,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ## [0.43.0] - 2019-01-25
 ### Added
 - Added event props `n_blur` and `n_clicks` - along with `n_blur_timestamp` and `n_clicks_timestamp` - in `Textarea` components, to maintain the functionality lost by removing the `click` and `blur` events. All other events were already covered by existing props. [#444](https://github.com/plotly/dash-core-components/pull/444)
+- Merged in R `dashCoreComponents` package and updated to 0.43.0
 
 ### Fixed
 - Fix dynamically disabling and enabling `Interval` components [#436](https://github.com/plotly/dash-core-components/pull/436)