Acknowledge XML Entity Definitions for Characters

See whatwg/html-build#42 (comment) for context.

source

@@ -107024,6 +107024,10 @@ document.body.appendChild(text);
   <p><i>The glyphs displayed above are non-normative. Refer to the Unicode specifications for formal
   definitions of the characters listed above.</i></p>
 
+  <p class="note">The character reference names originate from the <cite>XML Entity Definitions for
+  Characters</cite> specification, though only the above is considered normative. <ref
+  spec=XMLENTITY></p>
+
 
   <h2 split-filename="xhtml"><dfn id="xhtml">The XHTML syntax</dfn></h2>
 
@@ -117548,6 +117552,9 @@ INSERT INTERFACES HERE
    <dt id="refsXML">[XML]</dt>
    <dd><cite><a href="http://www.w3.org/TR/xml/">Extensible Markup Language</a></cite>, T. Bray, J. Paoli, C. Sperberg-McQueen, E. Maler, F. Yergeau. W3C.</dd>
 
+   <dt id="refsXMLENTITY">[XMLENTITY]</dt>
+   <dd>(Non-normative) <cite><a href="http://www.w3.org/2003/entities/2007doc/">XML Entity Definitions for Characters</a></cite>, D. Carlisle, P. Ion. W3C.</dd>
+
    <dt id="refsXMLNS">[XMLNS]</dt>
    <dd><cite><a href="http://www.w3.org/TR/xml-names/">Namespaces in XML</a></cite>, T. Bray, D. Hollander, A. Layman, R. Tobin. W3C.</dd>