[v1.1/dataReference] Fix type naming conventions

v1.1/datareference/datadoi.xml

@@ -13,7 +13,7 @@
           can be added via the reference description section              -->
     <!-- *********************************************************        -->
     <section>
-        <type>DataReference</type>
+        <type>data_reference</type>
         <name>DataDOI</name>
         <definition>A published dataset referenced by a DOI. The referenced dataset will contain either the odML file itself or the data the odML is annotating.
         </definition>

v1.1/datareference/datauri.xml

@@ -13,7 +13,7 @@
           can be added via the reference description section              -->
     <!-- *********************************************************        -->
     <section>
-        <type>DataReference</type>
+        <type>data_reference</type>
         <name>DataURI</name>
         <definition>A published dataset referenced by a URI. The referenced dataset will contain either the odML file itself or the data the odML is annotating.
         </definition>

v1.1/datareference/dataurl.xml

@@ -13,7 +13,7 @@
           can be added via the reference description section              -->
     <!-- *********************************************************        -->
     <section>
-        <type>DataReference</type>
+        <type>data_reference</type>
         <name>DataURL</name>
         <definition>A published dataset referenced by a URL. The referenced dataset will contain either the odML file itself or the data the odML is annotating.
         </definition>

v1.1/datareference/referencedescription.xml

@@ -8,7 +8,7 @@
     <!--         Data reference description  section               -->
     <!-- ********************************************************* -->
     <section>
-        <type>DataReference</type>
+        <type>data_reference/description</type>
         <name>DataReferenceDescription</name>
         <definition>Description of a data reference. This Section is defined to be used as a subsection of the 'DataReference' type sections.</definition>