Prepare changelog for v4.12.0

Author: BPScott

CHANGELOG.md

@@ -8,6 +8,34 @@ The format is based on [these versioning and changelog guidelines](https://git.i
 
 ---
 
+## 4.12.0 - 2020-01-27
+
+### Enhancements
+
+- Added a split variant to `Button` ([#2329](https://github.com/Shopify/polaris-react/pull/2329))
+- Allow DataTable headers to be React Elements ([#2635](https://github.com/Shopify/polaris-react/pull/2635))
+- Added support for explicit order of items in `ActionMenu` ([2057](https://github.com/Shopify/polaris-react/pull/2057))
+- Made the `DataTable` horizontal `Navigation` optional ([#2647](https://github.com/Shopify/polaris-react/pull/2647))
+
+### Bug fixes
+
+- Fixed `ReferenceError: React is not defined` in `Button` for the `esnext` build ([#2657](https://github.com/Shopify/polaris-react/pull/2657))
+- Fixed scrolling with scrollbar not working in Popover when content changes on scroll ([#2627](https://github.com/Shopify/polaris-react/pull/2627))
+- Fixed side-effects from being create during `Modal`s render ([#2644](https://github.com/Shopify/polaris-react/pull/2644))
+- Work around a build crash when using create-react-app due to a bug in css parsing in `postcss-custom-properties` ([#2643](https://github.com/Shopify/polaris-react/pull/2643))
+- Removed the `visited` CSS styling for tabs using the `url` prop ([#2639](https://github.com/Shopify/polaris-react/pull/2639))
+
+### Development workflow
+
+- Reworked the yarn splash Github comment and added average splash zone information ([#2649](https://github.com/Shopify/polaris-react/pull/2649))
+- Re-enabled the web unit tests in the consumer build test ([#2663](https://github.com/Shopify/polaris-react/pull/2663))
+
+### Code quality
+
+- Converted `/tests/build.test.js` to TypeScript ([#2617](https://github.com/Shopify/polaris-react/pull/2617))
+- Use `export *` to rexport component content in component indexs and subcomponent listings ([#2625](https://github.com/Shopify/polaris-react/pull/2625))
+- Use `export *` to rexport utility content ([#2636](https://github.com/Shopify/polaris-react/pull/2636))
+
 ## 4.11.0 - 2020-01-17
 
 ### Breaking changes

UNRELEASED.md

@@ -4,32 +4,14 @@
 
 ### Enhancements
 
-- Added a split variant to `Button` ([#2329](https://github.com/Shopify/polaris-react/pull/2329))
-- Allow DataTable headers to be React Elements ([#2635](https://github.com/Shopify/polaris-react/pull/2635))
-- Added support for explicit order of items in `ActionMenu` ([2057](https://github.com/Shopify/polaris-react/pull/2057))
-- Made the `DataTable` horizontal `Navigation` optional ([#2647](https://github.com/Shopify/polaris-react/pull/2647))
-
 ### Bug fixes
 
-- Fixed `ReferenceError: React is not defined` in `Button` for the `esnext` build ([#2657](https://github.com/Shopify/polaris-react/pull/2657))
-- Fixed scrolling with scrollbar not working in Popover when content changes on scroll ([#2627](https://github.com/Shopify/polaris-react/pull/2627))
-- Fixed side-effects from being create during `Modal`s render ([#2644](https://github.com/Shopify/polaris-react/pull/2644))
-- Work around a build crash when using create-react-app due to a bug in css parsing in `postcss-custom-properties` ([#2643](https://github.com/Shopify/polaris-react/pull/2643))
-- Removed the `visited` CSS styling for tabs using the `url` prop ([#2639](https://github.com/Shopify/polaris-react/pull/2639))
-
 ### Documentation
 
 ### Development workflow
 
-- Reworked the yarn splash Github comment and added average splash zone information ([#2649](https://github.com/Shopify/polaris-react/pull/2649))
-- Re-enabled the web unit tests in the consumer build test ([#2663](https://github.com/Shopify/polaris-react/pull/2663))
-
 ### Dependency upgrades
 
 ### Code quality
 
-- Converted `/tests/build.test.js` to TypeScript ([#2617](https://github.com/Shopify/polaris-react/pull/2617))
-- Use `export *` to rexport component content in component indexs and subcomponent listings ([#2625](https://github.com/Shopify/polaris-react/pull/2625))
-- Use `export *` to rexport utility content ([#2636](https://github.com/Shopify/polaris-react/pull/2636))
-
 ### Deprecations