Merge pull request facebook#2165 from DJCordhose/patch-1

Update 09.5-clone-with-props.md

Author: zpao

docs/docs/09.5-clone-with-props.md

@@ -18,3 +18,4 @@ Do a shallow copy of `component` and merge any props provided by `extraProps`. P
 > ```js
 > var clonedComponent = cloneWithProps(originalComponent, { key : originalComponent.props.key });
 > ```
+> `ref` is another prop that is not preserved either.