Add v6.1.0 to CHANGELOG.md [skip ci]

Author: Austin Green

CHANGELOG.md

@@ -12,6 +12,20 @@ _Note: Gaps between patch versions are faulty, broken or test releases._
 <!-- DO NOT MODIFY BELOW THIS COMMENT -->
 <!-- insert-new-changelog-here -->
 
+## v6.1.0 (2019-06-26)
+
+#### :rocket: New Feature
+* `dropdowns`, `notifications`
+  * [#371](https://github.com/zendeskgarden/react-components/pull/371)  feat(dropdowns): migrate react-dropdowns to Typescript ([@austin94](https://github.com/austin94))
+
+##### Typescript Support
+
+The `dropdowns` package is now written in [Typescript](https://www.typescriptlang.org/). The API has
+not been changed, but Type definitions are now included with the package.
+
+If you are not using Typescript in your development environment you will still benefit from
+improved autocompletion and documentation in certain IDEs and editors like VSCode.
+
 ## v6.0.3 (2019-06-20)
 
 #### :bug: Bug Fix