feat: Add CONTRIBUTING.md with clear contribution guidelines

[Copilot]

• Understand repository structure and existing documentation
• Create CONTRIBUTING.md with clear guidelines on what contributions will be accepted
• Define contribution types: prompt content, corrections, enhancements
• Include process for submitting contributions
• Reference SSOT files and avoid duplication
• Update TODO.md to mark task P3-28 as done
• Update README.md to reference CONTRIBUTING.md
• Fix Markdown syntax errors: Add missing blank lines around lists and code blocks

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Create a CONTRIBUTING.md</issue_title>
<issue_description>Create a CONTRIBUTING.md that articulates clearly what will and won't be accepted as a contribution for this repository, and how to contribute.

Current thinking:

• The purpose of the repository is educational, so all prompt content must be thoroughly commented.
• The repository is not a prompt library, only new custom prompts that provide examples of how to prompt and set up a repository will be accepted.
• Corrections to existing configuration/prompts will be accepted (e.g. typos, fixes for changing functionality of Copilot)
• Enhancements to existing configuration/prompts (e.g. improved technique)
• Enhancements to documentation
• Enhancements to GitHub repository configuration</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #5

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💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[pidster]

@copilot fix the Markdown lists, they're failing syntax checks due to missing whitespace

[Copilot]

@copilot fix the Markdown lists, they're failing syntax checks due to missing whitespace

Fixed in 920571c. Added blank lines around all lists and code blocks, and specified language for code blocks (text/markdown) to pass markdown linting.

[pidster]

@copilot rebase this from main

[Copilot]

@copilot rebase this from main

I cannot perform a rebase operation because:

1. Git rebase typically requires force push to update the remote branch, which I don't have access to (as stated in my limitations: "You cannot use git rebase to change commit history as force push is not available")
2. I cannot fetch from the remote repository due to authentication constraints
3. The repository appears to be a shallow clone with grafted history

To rebase this branch from main, you'll need to do it manually:

git fetch origin main
git rebase origin/main
git push --force-with-lease origin copilot/create-contributing-md

Would you like me to help with something else instead?

[pidster]

I think this is an adequate version to start with.