Treemap tooltip bad position on mobile

Description

The default position of tooltip on treemap is below the pointer/mouse/touch position.
On Mobile, the tooltip will be effectively shown under the fingertip, very hard to see.

Steps to check or reproduce

Check https://naver.github.io/billboard.js/demo/#Chart.TreemapChart on mobile.

[netil]

Hi @J4gQBqqR, thanks for the suggestion.
It's really hard to determine best suitable tooltip position for general use cases on mobile.

For those cases which needs to update the position, recommend adjusting by tooltip.position option.