fix(skills): clarify grill list formatting

src/skills/grill/SKILL.md

@@ -66,6 +66,11 @@ When code contradicts the user's claim, quote both the claim and the code behavi
 
 ## Open-question accounting
 
+Write each open question as its own top-level line.
+Start each line with one prefix, one space, one bracket state, one space, then the title.
+Indent cause notes by two spaces under the changed question.
+Do not nest open questions under other open questions.
+
 Use the line prefix to show list changes on the current turn:
 
 - `-` for unchanged, resolved, or removed questions