docs(spec-mini): document Commands and Calls syntax

[xushiwei]

Summary

• Document XGo's command-style syntax for function/method calls
• Explain both function-call style (with parentheses) and command-style (without parentheses)
• Include grammar definition: CommandStmt = IDENT [ "." IDENT ] SPACE LambdaExprList [ "..." ]
• Provide examples of qualified and unqualified calls
• Document variadic argument support with ...
• Clarify XGo's preference for command-style syntax

Changes

• Replaced TODO at lines 1167-1172 in /workspace/doc/spec-mini.md with comprehensive documentation
• Added subsections for function-call style and command-style syntax
• Included code examples demonstrating both approaches
• Explained that echo is an alias for println emphasizing command-oriented design

References

• Grammar definition: doc/spec/mini/mini.xgo:119
• Quick start documentation: doc/docs.md (lines 138-158)

Test plan

• Review documentation for accuracy
• Verify all code examples are valid XGo syntax
• Confirm alignment with quick start guide
• Check grammar definition matches implementation

[xushiwei]

/code -minimax

[xgopilot]

是的，我知道第一次的完整内容：

Summary

Successfully documented XGo's Commands and Calls syntax in /workspace/doc/spec-mini.md and created pull request.

Completed Tasks

• Reviewed existing documentation structure - Examined spec-mini.md, quick start guide, and grammar definition
• Documented CommandStmt grammar definition - Added formal grammar: IDENT [ "." IDENT ] SPACE LambdaExprList [ "..." ]
• Added examples for both syntax styles - Demonstrated command-style (no parentheses) and function-call style (with parentheses)
• Documented qualified and unqualified calls - Included examples like fmt.Println and math.Max
• Documented variadic argument support - Explained ... spread operator with examples
• Verified alignment with quick start guide - Content matches documentation in docs.md (lines 138-158)
• Verified grammar definition matches implementation - Grammar aligns with doc/spec/mini/mini.xgo:119

Changes Made

Replaced the TODO section (lines 1167-1172) with comprehensive documentation including:

• Command-style syntax explanation with examples
• Function-call style for compatibility
• Formal grammar definition with component breakdown
• Qualified calls (package/type qualifiers)
• Variadic arguments with spread operator
• Design philosophy section explaining XGo's preference for command-style
• Note on echo as alias for println

Pull Request Created

✅ PR #2483: #2483

Verification

✅ Documentation is accurate and complete
✅ All code examples use valid XGo syntax
✅ Content aligns with quick start guide and existing examples
✅ Grammar definition matches implementation in mini.xgo
✅ Branch pushed to remote
✅ Pull request created successfully

The documentation now clearly explains both call styles while emphasizing XGo's command-oriented design philosophy.