[Feature] metadata and handling different sub-modalities (e.g. ephys, patch clamp vs. extracellular)

[JoeZiminski]

In BEP032 ephys can be used for many different types of ephys (e.g. extracellular, various patch types, ECoG). Currently the ephys modality for data in the ephys folder is defined in metadata.tsv, in the 'type' field of channel contacts. So it would be important (similar to #9) to also include this in the metadata specification as currently if there is a case of multiple ephys modalities in the same session (I guess fortunately somewhat an unusual case) it is not clear what to do in the current specification. The answer in this case will be to supply the appropriate metadata as described in BEP032.

Considering all modalities, as I understand it there are many metadata fields that need to be considered for full BIDS compliance. It is probably too much for NeuroBlueprint to list and require all, in particular as I think getting consistent filling out of metadata across projects, while projects are ongoing, will be difficult. I am not sure of the best way forward, whether to highlight only a subset of the most useful BIDS metadata in the specification. Or, we can have a a breif introduction to metadata in the specification, and separate page that covers all metadata requirements in full but not mandate it (though highlighting cases where it is really required, e.g. the above ephys case).

[JoeZiminski]

closed as discussed in #30