amend! Add non-IN RR classes to list of unsupported configurations

amend! Add non-IN RR classes to list of unsupported configurations

Document that non-IN RR class issues are out of CVE scope

CVE-2026-5946 covered assertion failures reachable only through the
handling of resource record classes other than Internet (IN).
Configuring zones or views with such classes is a supported feature;
document in the security assumptions that problems reachable only
through it cannot be the basis for CVE assignment.

Closes #5805

Assisted-by: Claude:claude-opus-4-8