Add missing changelog entry

Author: gaearon

CHANGELOG.md

@@ -17,6 +17,7 @@
 * Files with `.json` extension are now discovered ([@gaearon](https://github.com/gaearon) in [a11d6a](https://github.com/facebookincubator/create-react-app/commit/a11d6a398f487f9163880dd34667b1d3e14b147a))
 * Bug fixes from transitive dependencies are included ([#126](https://github.com/facebookincubator/create-react-app/issues/126))
 * Linting now works with IDEs if you follow [these](https://github.com/facebookincubator/create-react-app/blob/master/template/README.md#display-lint-output-in-the-editor) instructions ([@keyanzhang](https://github.com/keyanzhang) in [#149](https://github.com/facebookincubator/create-react-app/pull/149))
+* After building, we now print gzipped bundle size ([@lvwrence](https://github.com/lvwrence) in [#229](https://github.com/facebookincubator/create-react-app/pull/229))
 
 ### Global CLI (`create-react-app`)