add a data license element to the XML

[lkamb]

I propose the following structure for a data license element to be added to near the top of the current XML structure.

  <xs:element name="dataLicense"> <!-- see note below -->
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:string">
          <xs:attribute name="URL" type="xs:anyURI"/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

example:

This dataset has been dedicated to the public domain under a Creative Commons CC0 1.0 Universal (CC0 1.0) Public Domain Dedication.

For submissions to NCEI through the SDIS, CC0 1.0 and CC-BY 4.0 will be the only options. https://creativecommons.org/publicdomain/zero/1.0/ https://creativecommons.org/licenses/by/4.0/

Note: the camel-case dataLicense is used to be consistent with the rest of the elements in the OADS v0.2.2 schema. In a future revision, I hope to change everything to snake_case. Yes, I've come around.

[lkamb]

Please have a look and comment: https://data.pmel.noaa.gov/sdig/test/OAPMetadataEditor.html

Note that the XML element is near (or at, depending on content) the top of the xml document.