'updateAxisPointer' event is missing in the doc

[SanLeen]

updateAxisPointer is a very useful event to listen where item is hovered by mouse.

echarts_instance.on('updateAxisPointer', e => console.log(e)) works but never be mentioned in the doc.

please add it

thaks 🍵

event object

{
    "type": "updateaxispointer",
    "seriesIndex": 0,
    "dataIndexInside": 37,
    "dataIndex": 336,
    "axesInfo": [
        {
            "axisDim": "x",
            "axisIndex": 0,
            "value": 336
        },
        {
            "axisDim": "y",
            "axisIndex": 0,
            "value": 5188.092254685122
        },
        {
            "axisDim": "x",
            "axisIndex": 1,
            "value": 336
        }
    ]
}