add dataset_description in `bids-examples/synthetic/derivatives/fmriprep`

[Remi-Gau]

Is there any specific reason why there is no dataset_description.json in the derivatives of the synthetic dataset ?

Sort of trying to use bids-example to test a couple of things and unless I am mistaken I don't think that we have a "good" example of raw + derivatives for functional MRI in there.

ds001 + ds000001-fmriprep: I think they go together but some of run labels from the fmriprep derivatives are not zero padded like the those of the raw

synthetic data derivatives seems to be missing some required files in a typical derivatives.

maybe making the synthetic derivatives a bit more compliant could be nice.

PS: also asking this because some of the derivatives code I work checks that the derivatives datasets have least a dataset_description.json in them...

[Remi-Gau]

Also realizing that the synthetic dataset does not have valid bids derivatives name either...

[sappelhoff]

it all comes back to missing derivatives support in the validator, which has been on our to do since almost a year now 👼 ... or is it almost two?

EDIT: clarification --> without a dataset_description.json in derivatives, the bids-validator would have actually ignored that derivatives folder. So my comment above is not as relevant as I thought when I wrote it.