[Docs]: Update `README.md` to tabulate integrations

[teocns]

📘 Current State of Documentation

📖 Suggested Improvement

Going through the docs is really annoying because of integrations extending over multiple pages.

I suggest we enclose integrations in a single table, back-linking to their respective docs, to keep the doc reader-friendly and simple.

🔗 Affected Documentation Pages

No response

🔍 Additional Context

No response

🤝 Contribution

• [ ] Yes, I'd be happy to submit a pull request with these changes.
• [ ] I need some guidance on how to contribute.
• [x] I'd prefer the Agentops team to handle this update.