[MISC] Propose BEP025 MIDS

[josator2]

Add new proposal for Medical Population Imaging Data Structure.

[chrisgorgo]

Thanks!

you'll need to fix the markdown syntax before this can be merged

src/06-extensions.md
  56:110-56:111  warning  Misaligned table fence     table-pipe-alignment        remark-lint
  56:338-56:339  warning  Misaligned table fence     table-pipe-alignment        remark-lint
  56:415-56:416  warning  Misaligned table fence     table-pipe-alignment        remark-lint
           59:1  warning  Remove 1 line before node  no-consecutive-blank-lines  remark-lint

See https://github.com/bids-standard/bids-specification/blob/master/CONTRIBUTING.md#writing-in-markdown

[chrisgorgo]

Many thanks for sending this. @bids-standard/everyone please have a look at this new BEP proposing to extend BIDS to new body parts and radiological modalities: https://docs.google.com/document/d/1chZv7vAPE-ebPDxMktfI9i1OkLNR2FELIfpVYsaZPr4