chore: add example EventCatalog to README

Author: leggetter

README.md

@@ -5,6 +5,8 @@ Generated the following from a [Hookdeck](https://hookdeck.com?ref=github-hookde
 - Services: based on Hookdeck [Sources](https://hookdeck.com/docs/sources?ref=github-hookdeck-eventcatalog-generator) and [Destinations](https://hookdeck.com/docs/destinations?ref=github-hookdeck-eventcatalog-generator)
 - Events: based on Hookdeck [Requests](https://hookdeck.com/docs/requests?ref=github-hookdeck-eventcatalog-generator) to Sources and [Events](https://hookdeck.com/docs/events?ref=github-hookdeck-eventcatalog-generator) sent to Destinations
 
+![Example of EventCatalog with Services and Events generated by the Hookdeck EventCatalog Generator](docs/hookdeck-eventcatalog.png)
+
 ## Run the generator as a CLI
 
 ```sh