Take the count out of a rule about the absent value, since the vocabulary it counted has already grown past it

docs/architecture/14-api-contract/openapi.yaml

@@ -2739,7 +2739,7 @@ components:
             Where the chapter boundaries came from, passed through from the engine's manifest, or
             `null` when NO MANIFEST HAS ANSWERED YET.
 
-            ⚠ **`null` is not a fourth kind of cut, and it is not `none`.** `none` is a book the engine
+            ⚠ **`null` is not a KIND of cut at all, and it is not `none`.** (⚠ Said "a fourth kind" until 06.09, when the vocabulary already held four values and `null` would have been a fifth: the sentence was written in the three-value era and the count went stale under it. The number is gone rather than corrected, so the rule outlives the next value too.) `none` is a book the engine
             looked at and found one chapter in; `null` is a book it has not been asked about. Having no
             provenance and having a poor one are different facts, and only the second says anything
             about the book. Held by