fix(skills): avoid stale grill marker examples

src/skills/grill/SKILL.md

@@ -30,8 +30,7 @@ A completed grill summary is not an instruction to build.
 3. Start the session.
    Present the full open-question list in short form.
    Include titles only, not full question bodies.
-   Mark ready questions with `- [ ]`.
-   Mark blocked questions with `- [b]`.
+   Format each line with the escaped prefix and bracket state from [Open-question accounting](#open-question-accounting).
    Then ask the first numbered question in the same turn.
 
    Finish when the interview has started with exactly one numbered question.