enh: Documentation Needed on BIDS layout or change BIDS layout requirements

[tjhendrickson]

Hello,

I ran into an issue with the fMRI volume portion of the bids apps, at first I thought there might be some sort error with the code, but eventually I realized that the verbosity in which I set the metadata collection into json sidecars during my BIDS caused the script to fail.

I used the heudiconv tool to convert, however, I used the --minmeta flag to minimize the amount of metadata collected. I did this in order to limit the storage space taken up by my bids conversions.

It would be beneficial to users strapped with storage constraints to run this app with minimal BIDS metadata.