Add missing Changelog entry—thanks @elijahmanor!

Author: gaearon

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### Build Dependency (`react-scripts`)
 
+* When the bundle size changes, we now display the difference after build. ([@elijahmanor](https://github.com/elijahmanor) in [#340](https://github.com/facebookincubator/create-react-app/pull/340))
 * `npm install`ing a missing dependency now forces a rebuild. ([@gaearon](https://github.com/gaearon) in [#349](https://github.com/facebookincubator/create-react-app/pull/349))
 * Autoprefixer config now includes more commonly supported browsers. ([@kripod](https://github.com/kripod) in [#345](https://github.com/facebookincubator/create-react-app/pull/345))
 * All the configuration is now documented inline so ejecting doesn’t leave you in the dark. ([@gaearon](https://github.com/gaearon) in [#362](https://github.com/facebookincubator/create-react-app/pull/362))