docs: Add FAQ section for common questions about MemOS Memory OS

[meichuanyi]

Summary

This PR adds a comprehensive FAQ section to the README, covering common questions about MemOS:

Topics Covered

General:

• What is MemOS
• Difference from embedding-based memory solutions
• Supported LLM providers (OpenAI, Azure, Qwen, DeepSeek, MiniMax, Ollama, HuggingFace, vLLM)

Getting Started:

• Quick start guide (Cloud vs Self-Hosted)
• Configuration requirements

Core Features:

• Multi-Modal Memory (text, images, tool traces, personas)
• Multi-Cube Knowledge Base Management
• Memory Feedback & Correction
• MemScheduler (async operations with Redis Streams)

Plugins & Integration:

• OpenClaw plugin (Cloud + Local)
• Hermes Agent plugin (memos-local-plugin 2.0)
• MCP support

Performance:

• Accuracy improvements (+43.70% vs OpenAI Memory, +40.43% LongMemEval)
• Token savings (35.24%)

Troubleshooting:

• API key errors
• Docker issues
• Local plugin troubleshooting

Help & Resources:

• Documentation links
• ArXiv paper
• Awesome-AI-Memory
• Community channels

This FAQ helps new users understand MemOS's value proposition, get started quickly, and troubleshoot common issues.