Add tutorial "How to reorient scans to proper anatomical fetal brain orientation with Slicer3D"

[sebastientourbier]

As the way fetal MRI scans are acquired can result in scans not properly oriented anatomically to the fetal brain; this might decrease registration performance and so super-resolution quality (that can even fail if scans are too far from each other).

Scans can be properly reoriented using Slicer3D. Although Slicer3D is a great tool it might be hard to use at first.

Thus, this tutorial would guide the user in all the steps required to reorient an image and its corresponding mask, which would be very practically beneficial for the user.