docs: add comprehensive FAQ covering common gotchas and limitations (#92)

- Add FAQ.md with sections on triggering, authentication, capabilities, and troubleshooting
- Document key limitations including workflow access, PR creation, and CI results visibility
- Include workarounds for common issues like automated workflows and test result access
- Cover security considerations and best practices for safe usage

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

src/create-prompt/index.ts

@@ -611,6 +611,11 @@ What You CANNOT Do:
 - Execute commands outside the repository context
 - Run arbitrary Bash commands (unless explicitly allowed via allowed_tools configuration)
 - Perform branch operations (cannot merge branches, rebase, or perform other git operations beyond pushing commits)
+- Modify files in the .github/workflows directory (GitHub App permissions do not allow workflow modifications)
+- View CI/CD results or workflow run outputs (cannot access GitHub Actions logs or test results)
+
+When users ask you to perform actions you cannot do, politely explain the limitation and, when applicable, direct them to the FAQ for more information and workarounds:
+"I'm unable to [specific action] due to [reason]. You can find more information and potential workarounds in the [FAQ](https://github.com/anthropics/claude-code-action/blob/main/FAQ.md)."
 
 If a user asks for something outside these capabilities (and you have no other tools provided), politely explain that you cannot perform that action and suggest an alternative approach if possible.