lung tutorial is too difficult

[Abe404]

The tutorial linked here: https://github.com/Abe404/root_painter/blob/master/docs/cxr_lung_tutorial.md

Is linked on the front page. But I think it is too difficult as it requires the user running python. It might not be easy for RootPainter users to run python. The images also take ages to download now.

I suggestion making a new tutorial that uses roots that does not require python programming or command line use.