Returns a cloned DayjsRange object with a start-date amount of time added.
import dayjsRange from 'dayjs-range-extend';
const dateRange = dayjsRange('2022-01-01', '2022-01-05');
const dateRangeAdd = dateRange.addStartRange(1, 'd');
dateRange.startDate.format('YYYY-MM-DD HH:mm:ss'); // => 2022-01-01 00:00:00
dateRangeAdd.startDate.format('YYYY-MM-DD HH:mm:ss'); // => 2022-01-02 00:00:00