Don't add anchors to page titles

We are currently adding anchor links to all headings. This includes the
page titles, which is the one heading to which we really don't need a
link. The page title is also centered and the addition of the anchor
causes the normally visible part of the title to be nudged to rendered off
center. This is visually unappealing, so stop adding anchors to the page
titles.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>

themes/beautifulhugo/layouts/partials/footer_custom.html

 <script src="https://cdnjs.cloudflare.com/ajax/libs/anchor-js/4.2.2/anchor.min.js"></script>
 <script>
-anchors.add('h1,h2,h3,h4,h5,h6');
+anchors.add('h1,h2,h3,h4,h5,h6').remove('.page-heading > h1');
 </script>