docs: page.xsl: Fix headerlinks with new docutils

New docutils generates a <section> element rather than a <div
class='section'> as it did before thus breaking our headerlink
generator.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

docs/page.xsl

@@ -139,6 +139,9 @@
       <xsl:if test="./html:a/@id">
         <a class="headerlink" href="#{html:a/@id}" title="Link to this headline">&#xb6;</a>
       </xsl:if>
+      <xsl:if test="parent::html:section">
+        <a class="headerlink" href="#{../@id}" title="Link to this headline">&#xb6;</a>
+      </xsl:if>
       <xsl:if test="parent::html:div[@class='section']">
         <a class="headerlink" href="#{../@id}" title="Link to this headline">&#xb6;</a>
       </xsl:if>