[Demo] Replace Kapa.ai with Streamlit app using Cortex.

[sfc-gh-tteixeira]

Replace Kapa.ai with Streamlit app using Cortex.

PS: The code should be good enough for review, but this PR is just meant as a demo right now.
PS2: I merged #1255 into this one so the build works and we get a proper demo.

📚 Context

Kapa costs money. Meanwhile, Snowflake Cortex now supports everything we need to build a chatbot. Let's give Cortex a try?

🧠 Description of Changes

• Replace Kapa with a Cortex-based assistant
• The assistant is just an iframed https://st-assistant.streamlit.app/
• This PR also adds a script to prep our markdown data for Cortex.

Current:

Revised:

💥 Impact

Size:

• Small
• Not small

🌐 References

• Notion

Contribution License Agreement

By submitting this pull request you agree that all contributions to this project are made under the Apache 2.0 license.

[sfc-gh-tteixeira]

FYI if you're trying to recover this work, it's still in the cortex-chat branch: https://github.com/streamlit/docs/tree/cortex-chat