[Docs] Enhance example overview page

[leecalcote]

Current State

The academy overview page should describe all of the content types or none at all.

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Contributor Guide and Resources

• 📚 Instructions for contributing to academy-example
  • academy-template documentation site, example and theme
• 🎨 Wireframes and designs for Layer5 site in Figma (open invite)
• 🙋🏾🙋🏼 Questions: Layer5 Discussion Forum and Layer5 Community Slack