Merge pull request #52 from jxom/additional-codemod-info-in-v16-blog-post

Modify v16 blog post upgrading section to elaborate on codemods

content/blog/2017-09-26-react-v16.0.md

@@ -134,6 +134,9 @@ Refer to the documentation for [detailed installation instructions](/docs/instal
 
 Although React 16 includes significant internal changes, in terms of upgrading, you can think of this like any other major React release. We've been serving React 16 to Facebook and Messenger.com users since earlier this year, and we released several beta and release candidate versions to flush out additional issues. With minor exceptions, **if your app runs in 15.6 without any warnings, it should work in 16.**
 
+For deprecations listed in [packaging](#packaging) below, codemods are provided to automatically transform your deprecated code.
+See the [15.5.0](https://reactjs.org/blog/2017/04/07/react-v15.5.0.html) blog post for more information, or browse the codemods in the [react-codemod](https://github.com/reactjs/react-codemod) project.
+
 ### New deprecations
 
 Hydrating a server-rendered container now has an explicit API. If you're reviving server-rendered HTML, use [`ReactDOM.hydrate`](/docs/react-dom.html#hydrate) instead of `ReactDOM.render`. Keep using `ReactDOM.render` if you're just doing client-side rendering.