add back anchor dfn-rdf-literal

Author: pchampin

spec/index.html

@@ -951,7 +951,7 @@ <h3>Literals</h3>
 
     <p>Literals are used for values such as strings, numbers, and dates.</p>
 
-    <p>A <dfn id="dfn-literal" class="export" data-lt="RDF literal">literal</dfn> consists of
+    <p>A <span id="dfn-rdf-literal"><!-- obsolete term --></span><dfn id="dfn-literal" class="export" data-lt="RDF literal">literal</dfn> consists of
       two, three, or four components, as below:</p>
 
     <ol>