Add link to MDN example and Service Worker Cookbook repo for examples

Author: marco-c

README.md

@@ -574,6 +574,15 @@ object will contain:
 </tbody>
 </table>
 
+# Help
+
+**MDN**
+
+There's an example on [MDN](https://developer.mozilla.org/en-US/docs/Web/Progressive_web_apps/Tutorials/js13kGames/Re-engageable_Notifications_Push)
+
+Also, the [Service Worker Cookbook](https://github.com/mdn/serviceworker-cookbook) is full of Web Push
+examples using this library.
+
 # Running tests
 
 > Prerequisites: