Janine notes not yet moved to correct place in repo

Add citation functionality to the instrument content type (all on the dev site).

Best code is currently in our ezid-linkage branch. Merge to main.

Adam created a drupal template - tpl.fip file to style the citation

Set up a custom field by calling hook-field-extra-fields

Adam - a dataset can have multiple archive records - institutional repository, data one, NCEI for archiving. Each different repository sends back a different persistent identifier. Adam's site: http://www.bco-dmo.org/dataset/3766

Identifier content type is attached to the archive (Adam) or node (Janine) as an entity reference