How to group the rows , under a row

[AdityaKallur]

How to group the rows , under a row

[pradeepnschrodinger]

Following the suggestions from #299 (comment):

1. If you just need to render some content underneath a row, you can use the rowExpanded prop to pass in a custom react component (refer the expanded rows example).
   You could also render sub tables as the expanded content.

2. Render the rows as you want and use the first columns' cell renderers to give a UX feel of column grouping.

I'm closing the issue, but feel free to continue the discussion here.