Add comprehensive FAQ documentation for user troubleshooting

[Copilot]

Created comprehensive FAQ documentation (FAQ.md) in Chinese to help users troubleshoot common credential management issues. The documentation is based on deep source code analysis to capture all error conditions and exception entry points.

Coverage

8 credential types documented:

• AccessKey, STS, ECS RAM Role (IMDSv1/v2), RAM Role ARN, OIDC (Kubernetes RRSA), Credentials URI, Bearer Token, RSA Key Pair

16 major sections, 70+ Q&A items:

• General issues (credential type selection, error messages)
• Environment variables (missing vars, naming conventions)
• Configuration files (INI/JSON format, profile management)
• Default credential chain (provider order, debugging)
• Network issues (timeouts, proxies, SSL/TLS, DNS)
• Security best practices (credential management across environments)
• Troubleshooting workflows

Key features:

• All error messages extracted from source code
• Each issue includes: error text, root cause, solution with code examples
• Quick reference tables for credential types and environment variables
• Platform-specific guidance (ECS, Kubernetes, local development)

Source analysis:

• 20+ provider implementations analyzed
• All error handling paths documented
• Parameter validation failures captured
• Network communication errors catalogued

Files Added

• FAQ.md (1,298 lines) - Main FAQ documentation
• FAQ_SUMMARY.md (122 lines) - Documentation overview and maintenance guide

You need to complete

• documentation is changed or added

Original prompt

仔细阅读当前项目的代码，不仅仅是readme文件， 帮我生成一份项目的说明文档，这个文档主要用于用户在使用此项目的答疑，因此你判断一下可能存在问题都应该写到faq中，特别应该注意到代码中的异常进入条件，这些都可能是用户出错的case。因此你应该将可能出现的问题详细的列出来，最后的结果用markdown格式来存储。

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