chore: deprecate markdown component

[farnabaz]

🔗 Linked issue

resolves #1434

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• [] 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

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[atinux]

Following the discussion in #1434

In that case I prefer to name it <ContentSlot /> directly, the idea of naming it <RichSlot /> was that it is actually a<slot/> but with the unwrap capability.