Link to lungman in readme does not work

[lauramurgatroyd]

https://github.com/TomographicImaging/gVXR-Tutorials/blob/main/notebooks/output_data/lungman/k3d_screenshot.png

[lauramurgatroyd]

I think it should be updated to this?
https://github.com/TomographicImaging/gVXR-Tutorials/blob/main/notebooks/output_data/lungman/k3d_screenshot-cropped.png