docs: the failures-only setting says the unsure rows are left out too

docs/4-implementation/swarm/review-classifier.md

@@ -241,7 +241,8 @@ replaces it.
   answer for as long as the biggest run the limit allows
 - `failures_only`: a boolean, `false` by default (also for a document stored
   before the field existed). When `true`, a posted PR review lists only the
-  rows that failed their rule, the ones that make it ask for changes, and an
+  rows that failed their rule, the ones that make it ask for changes, so the ❔
+  rows (below their threshold, or unsure) are left out too, and an
   approval says `No check failed.` in place of the table. A review with no
   verdict, and a try-out, always show every row
 - `runtime`: `api-key` or `acp` (see [Runtimes](#runtimes))