Added unstable_batchedUpdates as breaking change to v16 post (#10954)

* Add breaking change

ReactDOM.unstable_batchedUpdates now only takes one argument.

* Reword

* Update CHANGELOG.md

_posts/2017-09-26-react-v16.0.md

@@ -162,6 +162,7 @@ React 16 includes a number of small breaking changes. These only affect uncommon
 * `componentDidUpdate` lifecycle no longer receives `prevContext` param. (See [#8631](https://github.com/facebook/react/issues/8631))
 * Shallow renderer no longer calls `componentDidUpdate` because DOM refs are not available. This also makes it consistent with `componentDidMount` (which does not get called in previous versions either).
 * Shallow renderer does not implement `unstable_batchedUpdates` anymore.
+* `ReactDOM.unstable_batchedUpdates` now only takes one extra argument after the callback.
 
 ### Packaging
 
@@ -205,4 +206,4 @@ global.requestAnimationFrame = function(callback) {
 
 As always, this release would not have been possible without our open source contributors. Thanks to everyone who filed bugs, opened PRs, responded to issues, wrote documentation, and more!
 
-Special thanks to our core contributors, especially for their heroic efforts over the past few weeks during the prerelease cycle: [Brandon Dail](https://twitter.com/aweary), [Jason Quense](https://twitter.com/monasticpanic), [Nathan Hunzaker](https://twitter.com/natehunzaker), and [Sasha Aickin](https://twitter.com/xander76).
+Special thanks to our core contributors, especially for their heroic efforts over the past few weeks during the prerelease cycle: [Brandon Dail](https://twitter.com/aweary), [Jason Quense](https://twitter.com/monasticpanic), [Nathan Hunzaker](https://twitter.com/natehunzaker), and [Sasha Aickin](https://twitter.com/xander76).