Update CONTRIBUTING.md

[thatblindgeye]

Because

Currently we have a contributing guide in our org .github directory as well as our web app repo. We should only have one source of truth, so this helps split out repo specific content only to its repo while also linking to the "general" contributing content.

This PR

Issue

Closes #XXXXX

Additional Information

Pull Request Requirements

• [ ] I have thoroughly read and understand The Odin Project Contributing Guide
• [ ] The title of this PR follows the keyword: brief description of change format, using one of the following keywords:
  • Feature - adds new or amends existing user-facing behavior
  • Chore - changes that have no user-facing value, refactors, dependency bumps, etc
  • Fix - bug fixes
• [ ] The Because section summarizes the reason for this PR
• [ ] The This PR section has a bullet point list describing the changes in this PR
• [ ] I have verified all tests and linters pass after making these changes.
• [ ] If this PR addresses an open issue, it is linked in the Issue section
• [ ] If applicable, this PR includes new or updated automated tests