[Docs] Update and clean existing docs for better readability

[dot-agi]

Update and clean existing docs for better readability

Makes the integrations docs page and examples cleaner and more structured for improved developer UX.

Changelog

• Add docs page for AI21
• Add docs page for Groq ([Docs]: Groq support #454)
• Add docs page for Mistral AI
• Removes the link_to_api_button script from the docs pages
• Overhauled the integrations page structure for all providers
• Cleaned Anthropic example notebooks
• Updated Examples pages with the latest integrations
• Populated Multi Session examples page
• Removed LangChain v0.1 example from the page and pointed to the notebook instead
• Many small fixes to improve quality and accuracy

[areibman]

Good stuff thanks @the-praxs !!