Document a pub item (#8374)

substrate/frame/staking/src/lib.rs

@@ -805,6 +805,8 @@ impl<Balance: Default> EraPayout<Balance> for () {
 	}
 }
 
+/// Adaptor to turn a `PiecewiseLinear` curve definition into an `EraPayout` impl, used for
+/// backwards compatibility.
 pub struct ConvertCurve<T>(sp_std::marker::PhantomData<T>);
 impl<
 	Balance: AtLeast32BitUnsigned + Clone,