The current DTD for the JATS writer template is for Journal Publishing (JATS-journalpublishing1.dtd), which does not permit ext-link as a valid child (https://jats.nlm.nih.gov/publishing/tag-library/1.1/element/publisher-name.html).
This update modifies the default output template to be the less restrictive JATS archiving and interchange DTD which systems like PubMed use internally to represent their articles.
Modified template to include a `<back>` and `<body>` section.
This should give authors more flexibility, e.g. to put
acknowledgements metadata in `<back>`. References are
automatically extracted and put into `<back>`.