Fix event handler code sample
Fix event handler code sample

Summary:
We're using `withLayout()`, so we need to use `build()` instead of
`buildWithLayout()`.

Fix #172

Reviewed By: mihaelao

Differential Revision: D5002196

fbshipit-source-id: 4600c87ce14900f950633ff503321d1e112baaa7

facebook/litho,facebook/litho,facebook/litho,facebook/litho,facebook/litho,facebook/litho