Add content on attribution for code generated by AI agents or assistants

[woitaszek]

Pull Request Template

What are you trying to address

• Expand Git Guidance section to include content on techniques that may be useful for attributing and tracking AI-generated code in repositories, including:
  • How GitHub SWE Agent uses Co-authored-by trailers to denote authorship similar to pair programming
  • How a team might choose to use a custom trailer as part of a convention on tracking commits with substantial AI authorship
  • How to use git trailers in general ("Who knew!?")

I did not fully revise/refresh the page about GitHub's VS Code extensions.

Checklist

READY TO PR? Use the check-list below to ensure your branch is ready for PR.

• Changes follow the repo structure and land in the appropriate folder and section
• No confidential information
• No duplicated content
• Labeled appropriately
• [] This PR was reviewed by at least one subject matter expert
• No lint check errors related to your changes

Note: You may see link check errors on pages you have not touched. This is normal, and due to either broken links or sites that reject link checker bots. The reviewer will help you get to a green state on these.

[woitaszek]

I am reviewing where to place this content for effectiveness. I think that I should add some git trailers information to the main page about Git, and update the page about using coding assistants to include the example suggestions about attribution.