add changelog entry and change group to chnagelog docs

CHANGELOG.md

@@ -4,7 +4,11 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [these versioning and changelog guidelines][changelog-guidelines].
 
-<!-- Unreleased -->
+## Unreleased
+
+### Development workflow
+
+- Renamed `yarn start:vrt` to `yarn tophat` and updated the folder name to match ([#1754](https://github.com/Shopify/polaris-react/pull/1754), [#1764](https://github.com/Shopify/polaris-react/pull/1764))
 
 ## 2.4.0 - 2018-07-12
 

documentation/Versioning and changelog.md

@@ -19,6 +19,7 @@ The possible groups in which to categorize changes are:
 - Bug fixes
 - Documentation
 - Dependency upgrades
+- Development workflow (new yarn commands or changes to existing commands)
 
 ## Out of scope for CHANGELOG.md