[Docs] README.md instructions are out of date

[leecalcote]

Current State

Outdated and incomplete content structure.

Desired State

Let's avoid repeating ourselves and instead point contributors and learners to our docs.

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Contributor Guide and Resources

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