Add bonus objectives to some exercises.

data/workshop/exercise4.mdx

@@ -2,7 +2,7 @@
 title: Deploying an application via helm chart
 exercise: 4
 date: '2023-12-06'
-tags: ['openshift','containers','kubernetes','deployments','autoscaling']
+tags: ['openshift','containers','kubernetes','deployments','helm']
 draft: false
 authors: ['default']
 summary: "Exploring alternative deployment approaches."
@@ -131,4 +131,10 @@ Enter the `gitea` confirmation at the prompt and click **Delete**. If you now re
 | *Deleting the gitea application helm release*                       |
 </Zoom>
 
+
+## 4.6 - Bonus objective: Artifact Hub
+
+If you have time, take a while to explore https://artifacthub.io/packages/search to see the kinds of applications available in the most popular publicly available Helm Chart repository Artifact Hub.
+
+
 Well done, you've finished exercise 4! 🎉