Update XML schema and schematron Reference URIs
Please use this for the Schematron information:
<?xml-model href="https://pds.nasa.gov/pds4/pds/v1/PDS4_PDS_1A00.sch" type="application/xml"
schematypens="http://purl.oclc.org/dsdl/schematron"?>
Please use this for the schemaLocation:
<Product_Observational xmlns="http://pds.nasa.gov/pds4/pds/v1"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://pds.nasa.gov/pds4/pds/v1
https://pds.nasa.gov/pds4/pds/v1/PDS4_PDS_1A00.xsd">