Document how to get new zoomed data range

[JMRCGuedes]

Hello guys!!

I'm trying to get the range x-axis values when i apply the zoom by dragging in the chart like in the following example:

[poiuytrez]

This is how I found what is selected:

onZoomComplete: function({chart}) {
              console.log(`I was zoomed!!!`);
              const start = new Date(chart.chart.boxes[2].min);
              const end = new Date(chart.chart.boxes[2].max);
              console.log(start);
              console.log(end);
            }

[kurkle]

chart.getZoomedScaleBounds() was added in #780