docs: improve api documentation for advanced chat and workflow

[kurokobo]

Checklist:

Important

Please review the checklist below before submitting your pull request.

• Please open an issue before creating a PR or link to an existing issue
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

Description

This PR improves API documentation for Advanced Chat App and Workflow App.

Please let me know if my language or translations are incorrect.

• For Advanced Chat App:
  • Add a brief description to specify a file as one of the inputs to support Single File type or File List type
    
  • Correct the description regarding the supported file formats for the File Upload API
    
• For Workflow App
  • Add a brief description to specify a file as one of the inputs to support Single File type or File List type
    
  • Add whole File Upload API section with corrected description about supported file format
    

Follow-Up for #9832 (Thanks @JzoNgKVO)
Fixes #9880

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update, included: Dify Document
• Improvement, including but not limited to code refactoring, performance optimization, and UI/UX improvement
• Dependency upgrade

Testing Instructions

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Deploy customized web image on Docker and ensure new docs are displayed in API Access page for the chatflow and workflow