findMinDayIndex $-$ Returns the index of the day with the least number of downtime hours. If there are

multiple days that have the same minimum number of hours, any of these indexes can be returned.

$($Depending on your code, it is likely to be the first or last one.$)$ Note: this method and the next return

the index, not the downtime. The main program will display both this index as well as the downtime.