[joss][nice to have] Provide demo data?

[sneakers-the-rat]

Part of: openjournals/joss-reviews#6336

Hello!!

as usual I like the dead simple "drag a nifti onto this big box" interface, and I see the bear_uchar.nii.gz used in the tests as example data. For the sake of reviewers and also for potential users, would it be possible to have a "demo mode" that loads that example file from the UI so folks can test it out without needing to have a nifti on hand?

edit: brainbox has a great example of what i mean with the demo data selector :).

[katjaq]

Thank you for the suggestion!
We implemented it in commit 58f8f09
Just one demo dataset – but we hope it's ok :)