Describe the measured tone and vibrance in DarkRoom's own terms

The calibration commits named DarkRoom's default curve after another
product and described vibrance as doing what another editor's does at
the same value. The curve is the DNG SDK's reference, so it is called
that; vibrance is scaled to deliver the strength its value names, as
measured against the photographer's earlier exports. Two test names
follow. The measurements and where they came from are unchanged.

core/dr-gpu/src/adjust.rs

@@ -3420,7 +3420,7 @@ mod tests {
             read_centre(&ctx, t)
         };
 
-        // The default rendering is Camera Raw's curve (D21); for a grey its
+        // The default rendering is the DNG reference curve (D21); for a grey its
         // ProPhoto round trip is the identity, so the reference applies as is.
         let scene = 3537.0 / 16383.0;
         let viewed = dr_pipeline::camera_raw::apply_reference(