🎉 Add macdown

[geeknik]

🪩 Provide a link to the proposed addition

https://github.com/MacDownApp/macdown

😳 Explain why it should be added

Markdown editor for MacOS with live preview and export to HTML or PDF.

📖 Additional context

No response

🧨 Issue Checklist

• I have checked for other similar issues
• I have explained why this change is important
• I have added necessary documentation (if appropriate)