xls reference list has H2 child

[StephDriver]

from axe testing as part of a11y audit.

Articles on all three themes are affected.

When there is a title for the reference section, this is inserted inside the reference list, rather than than before the list.

<div ... id="reflist">
<ul>
    <h2 id="heading6" class="section scrollspy">Reference</h2>
    <li> 
...

I think the problem is here:

        <div id="reflist">
          <ul>
            <xsl:apply-templates/>
          </ul>
        </div>
   

... 

    <xsl:template match="ref-list/title">
        <xsl:if test="node() != ''">
            <xsl:element name="h2">
                <xsl:attribute name="id">reference-header</xsl:attribute>
                <xsl:apply-templates/>
            </xsl:element>
        </xsl:if>
    </xsl:template>