docs: Add comprehensive FAQ section

[meichuanyi]

Summary

This PR adds a comprehensive FAQ section to help new users quickly understand LocalAGI and troubleshoot common issues.

Changes

• Created docs/FAQ.md with detailed FAQ covering:
  • General questions about LocalAGI and its differences from other frameworks
  • Installation and system requirements
  • Model configuration and customization
  • Features explanation (Skills, Knowledge Base, Connectors, MCP, Custom Actions)
  • Troubleshooting common issues
  • Getting help resources
• Added FAQ link in README.md

Benefits

• Reduces barrier to entry for new users
• Addresses common questions before they're asked
• Provides quick reference for core concepts
• Links to relevant documentation sections
• Helps users troubleshoot issues independently

FAQ Topics Covered

1. General: LocalAGI concept, comparison with LangChain/AutoGPT/CrewAI/OpenAI Operator
2. Installation: System requirements, Docker setup, source build
3. Models: Supported models, customization, cloud provider usage
4. Features: Skills, Knowledge Base, Connectors, Agent teams, MCP, Planning, Custom Actions
5. Troubleshooting: Startup issues, agent response, knowledge base, connectors, memory errors
6. Getting Help: Documentation links, YouTube videos, GitHub issues, Telegram bot

Checklist

• Documentation only change
• No code modifications
• FAQ content based on existing README and documentation
• Helpful for community adoption

This FAQ addition helps users understand LocalAGI's capabilities and troubleshooting at a glance.