Adopt GenAI usage guidelines from open-liberty repository

[kabicin]

Description

The Open Liberty Operator repository should adopt the GenAI (Generative AI) usage guidelines established in the main open-liberty repository to ensure consistent contribution standards across OpenLiberty projects.

Background

As AI-assisted development tools become more prevalent, we need clear guidelines for:

• How contributors should declare AI tool usage in their contributions
• Quality standards for AI-generated code
• Transparency requirements for tracking and auditing

The open-liberty repository has already established comprehensive GenAI guidelines that we should adopt to maintain consistency across the OpenLiberty ecosystem.

Proposed Changes

1. Add GENAI_GUIDELINES.md: Adopt the GenAI policy from open-liberty repository with any necessary adaptations for the operator-sdk context
2. Update CONTRIBUTING.md: Add reference to the GenAI guidelines in our contribution documentation
3. Establish commit message format: Require Co-authored-by-AI: <Tool> <Version> tag for AI-assisted contributions

Benefits

• Consistency: Aligns Open Liberty Operator with standards used across OpenLiberty projects
• Transparency: Clear identification of AI-generated code for tracking and auditing
• Quality assurance: Establishes expectations that AI-generated code meets the same standards as human-authored code
• Contributor clarity: Provides clear guidance on how to properly use and declare AI tools in contributions

Acceptance Criteria

• GENAI_GUIDELINES.md file added to repository root
• CONTRIBUTING.md updated to reference GenAI guidelines
• Guidelines include transparency requirements (commit message format)
• Guidelines include quality standards for AI-generated code
• Documentation is clear and actionable for contributors

References

• Open Liberty GenAI Guidelines
• Open Liberty CONTRIBUTING.md