docs: add FAQ section for common questions

[meichuanyi]

Summary

Add a comprehensive FAQ section to the README to help new users quickly find answers to common questions about BotSharp.

Changes

• Added FAQ section covering 12 common questions across 5 categories:
  • General Questions: What is BotSharp, .NET version support, licensing
  • LLM Provider Configuration: Supported providers, custom provider setup
  • Agent Development: Custom agent creation, multi-agent cooperation
  • MCP Integration: Model Context Protocol support
  • Deployment: Production deployment, headless API usage
  • Troubleshooting: Dependency errors, LLM timeout issues

Motivation

New users often have the same questions about getting started, configuring LLM providers, and deploying BotSharp. An FAQ section in the README reduces friction and directs users to the right resources.

Checklist

• Content is relevant to BotSharp's features and architecture
• Questions cover the most common user concerns
• Formatting follows the project's README style

[meichuanyi]

Hi! Just following up on this documentation PR. Would love to hear your thoughts when you have a moment. Thanks! 🙏

[meichuanyi]

Hi! Just following up on this PR. Would love to hear your thoughts on the FAQ section. Let me know if any changes are needed! 👋

[meichuanyi]

Hi! Just following up on this PR. Would appreciate a review when you have a moment. 🙏