Feature Request: Option to suppress "Generated by..." text

[beardofedu]

When agentic workflows operate and modify the content of issues (and I'm assuming PRs, but I haven't had them do anything in PRs yet to confirm) they post a line in the issue comment body that identifies that the text was modified/updated by the various agentic workflows leveraged. This was super helpful when I was running one agentic workflow to modify content of the issues, but as the number of workflows has increased, the number of "Generated by..." lines. An option to either suppress it via the UI or to be able to tell agentic workflows to limit/not display the Generated by content would be ideal.

[pelikhan]

At @copilot, the user can use the footer: false syntax in safe-outputs to disable adding footers. We should create an FAQ entry that answers the question in this issue and shows how the configuration is written. We should also add documentation about the footer field in safe-outputs, and update the various locations where we describe or use safe-outputs to mention this option.

[pelikhan]

We used a technical writer sub-agent to improve the documentation quality and ensure consistency across all gh-aw workflow descriptions.