feat(docs): add note for docker image

Author: swarna1101

docs/hackathon/0-onboarding.mdx

@@ -136,6 +136,13 @@ Ensure you have the following tools installed:
 
 **Happy building!**
 
+:::note[Important Note About Docker Images and GitHub Packages]
+**GitHub Container Registry (ghcr.io) packages are private by default.**
+
+If you're publishing Docker images that need to be pulled by the TEE environment, you'll need to make your package public in your GitHub repository settings.
+
+:::
+
 :::danger[Using hackathon compute resources]
 
 VM instances in `verifiable-ai-hackathon` are continuously monitored.