Followup new BIDS features

Michael Schirner suggested a set of new features into the BIDS format, to support TVB ready data.

On 15 sep from him:

Dear Lia,

thanks again for the great discussion yesterday.

Please find here the BIDS extension rendered as HTML and a demo data set:

---- private but downloaded on Codemart- science secure drive ----

The full standard can be accessed here:

https://bids-specification.readthedocs.io/

Since our PR
(https://github.com/bids-standard/bids-specification/pull/850) there was a
small update: the keys "NumberOfColumns", "NumberOfRows", "CoordsRows" and
"CoordsColumns" will no longer be generic metadata, but will only be
required for the datatypes "ts", "spatial", and "net".

Please let me know if there are any questions or suggestions.

Best,
Micha