This is really nice and easy way to add/remove row(s)/column(s) in table. As you probably know, Alt (Opt) key is used to duplicate objects, so it can also be used within table. Simply grab row/column edge and add Alt (Opt) key while dragging. You will instantly see the result! It’s so cool! This also works if you want to add row(s)/column(s) in middle of the table. Notice that InDesign will use width/height of previous row/column while adding new one(s).
To remove row(s)/column(s) do the same, but you have to drag to opposite direction.
Be aware that InDesign will delete row(s)/column(s) all together with its contents!