Update CronJob epilogue section to refer to new testing docs

docs/book/src/cronjob-tutorial/epilogue.md

@@ -4,16 +4,17 @@ By this point, we've got a pretty full-featured implementation of the
 CronJob controller, and have made use of most of the features of
 KubeBuilder.
 
+If you want to learn how to write integration tests for the CronJob kind
+built in this tutorial, take a look at the [Writing Tests](/reference/writing-tests.md)
+documentation.
+
 If you want more, head over to the [Multi-Version
 Tutorial](/multiversion-tutorial/tutorial.md) to learn how to add new API
 versions to a project.
 
 Additionally, you can try the following steps on your own -- we'll have
 a tutorial section on them Soon™: 
 
-- writing unit/integration tests (check out [envtest][envtest])
 - adding [additional printer columns][printer-columns] `kubectl get`
 
-[envtest]: https://godoc.org/sigs.k8s.io/controller-runtime/pkg/envtest
-
 [printer-columns]: /reference/generating-crd.md#additional-printer-columns