feat: robust docs

src/model/item.rs

@@ -8,7 +8,7 @@
 //! Keeping them adjacent is what turns a question bank into an instrument you
 //! can improve, because every administration produces a checkable prediction.
 //!
-//! One deliberate departure from a naive design: [`Calibration`] is cumulative
+//! One deliberate departure from a naive design: [`Calibration`] is *cumulative*
 //! rather than per-administration. Raw per-response data belongs in the Parquet
 //! tables under `data/`, which are far better at holding it, and an item's YAML
 //! holds the rolled-up estimate plus a list of which administrations went into