Add comment clarifying conversion from bars to beats in Simpler device build.

src/lib/exporters/ableton/builders.ts

@@ -558,7 +558,7 @@ async function buildSimplerDevice(koTrack: AblTrack, abletonVersion: AbletonVers
           '@BeatTime':
             koTrack.timeStretchBars *
             koTrack.timeSignature.numerator *
-            (4 / koTrack.timeSignature.denominator),
+            (4 / koTrack.timeSignature.denominator), // convert bars to beats
         },
       ];
   }