Aligning MP2RAGE example folders with example datasets

[lazaral]

Just trying to finish off some question marks from a pull request :)

One open question (@Gilles86 you might know?): my current version of the MP2RAGE example folders has a T1w scan, but I can't see it in the corresponding example datasets in OSF.

Was that just the main T1w structural scan or is it actually part of the scans needed for MP2RAGE? If it's the first case, I can remove it from the example folder in my pull request.

Originally posted by @lazaral in #38 (comment)