[dxwg] Pull Request: Added bib refs

andrea-perego has just labeled a pull request from andrea-perego for https://github.com/w3c/dxwg as "dcat":

== Added bib refs ==
Where missing. 

They concern: [!DATETIME], [DCTERMS], [!IANA-MEDIA-TYPES], [VOCAB-DATA-CUBE]. 

They are all available from Specref (no need to add them in the local biblio).

See https://github.com/w3c/dxwg/pull/191