Add react-native-enriched-markdown alternatives for legacy markdown libraries

[hryhoriiK97]

📝 Why & how

Adds react-native-enriched-markdown as the recommended alternative for three unmaintained markdown libraries: react-native-simple-markdown, react-native-markdown, and react-native-easy-markdown.
These libraries are no longer maintained, but still appear in search results and get regular downloads. Recommending react-native-enriched-markdown helps guide developers toward a modern, actively maintained option with New Architecture support.

✅ Checklist

• Added library to react-native-libraries.json
• Updated library in react-native-libraries.json

• Documented how you found or replicated the issue.
• Explained how you fixed the issue or built the feature.
• Described how to use or verify the change.

[Simek]

Hey @hryhoriiK97, thanks for the updates! 👍