add matomo snippet

_includes/scripts.html

+<!-- Matomo -->
+<script type="text/javascript">
+    var _paq = window._paq || [];
+    /* tracker methods like "setCustomDimension" should be called before "trackPageView" */
+    _paq.push(['trackPageView']);
+    _paq.push(['enableLinkTracking']);
+    (function() {
+      var u="https://howto-monitoring.lcsb.uni.lu/matomo/";
+      _paq.push(['setTrackerUrl', u+'matomo.php']);
+      _paq.push(['setSiteId', '2']);
+      var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
+      g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'matomo.js'; s.parentNode.insertBefore(g,s);
+    })();
+  </script>
+  <noscript><p><img src="https://howto-monitoring.lcsb.uni.lu/matomo/matomo.php?idsite=2&amp;rec=1" style="border:0;" alt="" /></p></noscript>
+  <!-- End Matomo Code -->
\ No newline at end of file