VEP-007: datalink-core#detached-header

[Baptiste Cecconi]

Hi all, 

I received an direct comment from Anne Raugh, and have updated the Rationale of VEP-007 accordingly. I copy the new content of the Rationale section below:

> Rationale:
> In some formats and archives, the metadata required to decode the 
> content of #this is in a separate file. In the case of NASA/PDS 
> data products, for example, the PDS label file contains the decoding 
> metadata. In some archives, the FITS header may be stored separately 
> as a plain text file, next to a data file consisting of a binary 
> stream of bytes. Clients would use the content type (MIME type) 
> (e.g.: application/x-pds4-label+xml, or text/x-pds3-label) to enable 
> the processing.
> 

Cheers
Baptiste