add comments to the code

assets/ts/thresholdCtl.ts

@@ -8,10 +8,12 @@ const threshold: number[] = [0, 40, 80, 120, 160, 200]
 export const thresholdSensitivityArray: number[] = [100, 40, 18, 14, 9, 5]
 export let thresholdIndex: number = 2
 
+// update inner text of threshold display element
 function thresholdUpdate(): void {
   thresholdDisp.innerText = duper(threshold[thresholdIndex])
 }
 
+// threshold control initialization
 export function thresholdCtlInit(): void {
   thresholdUpdate()
   const dec = document.getElementById('thresholdDec') as HTMLButtonElement