Document the survey banner as a version-aware feature

What does this MR do and why?

Updates versions.md to document that the Survey Banner component needs to be version-aware. It should never appear on an archived copy of the site.

Merge request acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this merge request.