docs: Add XML documentation to IYaml interface (#1511)

[thomhurst]

Summary

• Added comprehensive XML documentation to the IYaml interface following the same pattern as IJson
• Documented the interface summary describing its purpose
• Added documentation for all four methods: ToYaml<T> (2 overloads) and FromYaml<T> (2 overloads)
• Each method now has proper <summary>, <typeparam>, <param>, and <returns> documentation

Fixes #1511

Test plan

• Build verified with dotnet build src/ModularPipelines/ModularPipelines.csproj -c Release
• No breaking changes, documentation-only addition

🤖 Generated with Claude Code

[thomhurst]

Summary

Adds XML documentation comments to the IYaml interface.

Critical Issues

None found ✅

Suggestions

None - the documentation is clear, accurate, and follows standard C# XML doc conventions.

Verdict

✅ APPROVE - No critical issues

The documentation accurately describes the YAML serialization/deserialization methods and their parameters. This is a clean documentation-only change that improves the public API surface.

[Copilot]

Pull request overview

This PR adds comprehensive XML documentation to the IYaml interface, following the established pattern from the IJson interface. The documentation includes descriptions for the interface itself and all four methods (two serialization and two deserialization methods with their respective overloads).

• Added interface-level summary describing YAML serialization/deserialization functionality
• Documented all method signatures with proper <summary>, <typeparam>, <param>, and <returns> tags
• Maintained consistency with existing documentation patterns in the codebase