chore(xquery): address review comment

Author: duncdrum

src/main/xar-resources/data/xquery/xquery.xml

@@ -911,7 +911,10 @@
             that extend XPath and XQuery with cross-platform functions and capabilities. (Only those
             built into eXist are listed below; see eXist-db's Package Repository for others.)</para>
 
-
+        <sect2 xml:id="http-client-module">
+          <title>HTTP Client</title>
+          <para>eXist-db implements the <link condition="_blank" xlink:href="http://expath.org/spec/http-client">HTTP Client Module</link>, an EXPath specification for interacting with HTTP servers.</para>
+        </sect2>
         <sect2 xml:id="packaging-system">
             <title>Packaging System</title>
             <para>eXist-db implements the <link xlink:href="http://expath.org/spec/pkg">Packaging