issue_101: Resolve what the implementation answered

The ADR listed the matrix marker as open; this slice chose one, so the
bullet now names it instead of still asking. The suppression mechanism
for deliberately historical relations stays open and points at its
follow-up, because no artifact is retired yet and the warning volume it
would be weighed against does not exist.

Author: Dieter Baier

src/docs/arc42/09-architecture-decisions/adr-009-artifact-retirement-and-relation-validity.adoc

@@ -231,9 +231,12 @@ separation.
   outgoing `supersedes` relation.
 * How does an author record that a relation to a retired artifact is
   deliberately historical, so its warning does not become permanent build
-  noise?
+  noise? Deferred until the first retirements make the warning volume
+  observable.
 * How does a generated matrix mark an inactive relation, for example a marker
-  column, a footnote, or struck-through text?
+  column, a footnote, or struck-through text? Answered by the implementation:
+  an `(inactive)` marker on the relation type cell, carrying the
+  `relation-inactive` role. See xref:artifact-lifecycle-status[].
 
 === Review Notes