DOC: Diátaxis application to Source Tutorial part 2: Defacing Example

[nordme]

What does this implement/fix?

This PR applies Diátaxis framework principles to the "Source Alignment and Coordinate Frame" tutorial by removing defacing information from the source alignment tutorial and adding a "Deface Dig and MRI" example instead. This is the second PR in a series of three refactoring the original Source Alignment tutorial.

[wmvanvliet]

This is a really nice example! Given the amount of code, would it make sense to collect it in an mne.deface(mri) function?

[nordme]

This is a really nice example! Given the amount of code, would it make sense to collect it in an mne.deface(mri) function?

Thanks, @wmvanvliet! My initial instinct about defacing is that it's a task likely to generate a lot of edges cases or otherwise require a lot of customization. So my inclination would be to provide a recipe but avoid having to maintain a function. But I'm happy to discuss this with Dan and Eric and the rest of the team!

[larsoner]

For the deface question, mne-bids has deface option

https://mne.tools/mne-bids/stable/generated/mne_bids.write_anat.html

I think the easiest path forward would be to expose mne_bids.deface(mri) or similar, then use it here. @nordme could you make an issue on MNE-BIDS about this to see if people are open to it?