[CHANGELOG] Prepare v1.2.1

CHANGELOG.md

@@ -5,6 +5,60 @@ Material-UI strictly follows [Semantic Versioning 2.0.0](http://semver.org/).
 - Weekly release: patch or minor version at the end of every week for routine bugfix or new features (anytime for urgent bugfix).
 - Major version release is not included in this schedule for breaking change and new features.
 
+## 1.2.1
+###### *Jun 10, 2018*
+
+Big thanks to the 15 contributors who made this release possible.
+
+Here are some highlights ✨:
+- A lot of bug fixes 🐛!
+- Add full `React.createRef` support ⚛️ (#11757) @t49tran.
+- Document the `withWidth()` helper
+
+### Breaking change
+
+N/A
+
+#### Component Fixes / Enhancements
+
+- [Select] Add a placeholder demo (#11706) @oliviertassinari
+- [RootRef] Update RootRef.d.ts (#11708) @franklixuefei
+- [ButtonBase] Document the `type` property (#11728) @C-Rodg
+- [Popover] Fix default value (#11729) @oliviertassinari
+- [withWidth] Second iteration on the component (#11730) @oliviertassinari
+- [transition] Fix IE11 issue in dev mode (#11743) @adeelibr
+- [Tabs] Better flex layout (#11748) @adeelibr
+- [core] Add React.createRef support (#11757) @t49tran
+- [Grid] Improve the dev warnings (#11765) @oliviertassinari
+- [CircularProgress] Fix centering (#11781) @adeelibr
+- [TextField] Bind the focus/blur explicitly (#11789) @oliviertassinari
+- [RadioGroup] Fix onChange chaining (#11793) @oliviertassinari
+
+#### Docs
+
+- [docs] Property !== attribute (#11694) @adeelibr
+- [docs] Add Trafikito.com to showcase (#11716) @liesislukas
+- [docs] Update meetingku image (#11724) @liganok
+- [docs] Improve docs:dev init by ~2 s and HMR by ~200 ms (#11752) @tal952
+- [docs] Change app bar to button on the getting started (#11756) @Simperfit
+- [docs] Add React Most Wanted to related projects (#11753) @TarikHuber
+- [docs] Error in example in Migration From v0.x Guide (#11771) @AkselsLedins
+- [docs] Simple Grammar Fix (#11785) @jeff-kilbride
+- [docs] Fix typo (#11787) @BenDiuguid
+- [docs] Better troubleshooting action for the hydration mismatch (#11792) @oliviertassinari
+
+#### Core
+
+- [core] Remove parser specification to fix JSON issue (#11763) @ryanpcmcquen
+- [core] Throw if react >= 16.3.0 requirement isn't matched (#11779) @oliviertassinari
+- [core] Better warnings for class names duplicates (#11788) @oliviertassinari
+- [core] Remove dead code (#11791) @oliviertassinari
+
+#### Labs
+
+- [Slider] Fix for IE11 (#11727) @epodivilov
+- [Slider] Value can still be updated while disabled (#11744) @epodivilov
+
 ## 1.2.0
 ###### *Jun 3, 2018*