Added note about the browser bundle currently requiring React.addons for grid components

Closes #2

Author: insin

README.md

@@ -37,6 +37,10 @@ performs dead-code elimination, such as
 
 ### Browser bundle
 
+**Note: the browser bundle expects to be able to use `React.addons.cloneWithProps()`
+for grid components, so you must use the react-with-addons React bundle in order
+to make use of them.**
+
 The browser bundle exposes a global `BootstrapForm` variable and expects to
 find global `React` ([React](http://facebook.github.io/react/)) and `forms`
 ([newforms](https://github.com/insin/newforms)) variables to work with.