#214 docs(sessions): add PATCH /api/sessions/{sessionId}/chats/{chatId} endpoint for updating chat details

• Introduced a new PATCH endpoint to update session chat details, allowing for renaming and model ID updates.
• Added request and response schemas for PatchSessionChatRequest and CreateSessionChatResponse.
• Updated navigation to include the new PATCH endpoint under the Sessions group in the documentation.
• Enhanced the existing documentation to clarify the requirements for the request body and possible response statuses.

This change improves the API's functionality by providing users with the ability to modify existing session chats, enhancing overall user experience.

Summary by CodeRabbit

• New Features

  • Added API endpoint to update session chat properties including title and model ID.

• Documentation

  • Updated API documentation to include the new chat update endpoint.
  • Updated documentation navigation to reflect the new capability.