docs: update documents for multiple level drilldown - `childGroupId`#295

Merged

quillblue merged 11 commits intoapache:nextfrom tyn1998:docs/multi-drilldown

Oct 29, 2022

+205-16

Commits on Sep 19, 2022

all placeholders for multi-drilldown document
tyn1998
committed

Commits on Sep 20, 2022

finish series.data.groupId & series.data.childGroupId
tyn1998
committed

Commits on Sep 28, 2022

finish english docs for multiple levels downdrill feature
tyn1998
committed

Commits on Oct 23, 2022

use "parent" rather "father" and use "Apache ECharts" rather "Echarts"
tyn1998
committed