contract addresses reference

Based on WH feedback, I added a link to the reference page in the tutorial, where users can check the complete list of contract addresses.

[x] Required - I have added a label to this PR 🏷️
[x] Required - I have run my changes through Grammarly
[ ] If pages have been moved, I have created redirects in the wormhole-mkdocs repo

wormhole-foundation / wormhole-docs