add Matomo fix #284

Author: maelle

_output.yml

@@ -1,5 +1,7 @@
 bookdown::gitbook:
   css: style.css
+  includes:
+    in_header: matomo.html
   split_by: chapter
   config:
     sharing:

matomo.html

@@ -0,0 +1,6 @@
+<!-- Matomo -->
+<link rel="stylesheet" type="text/css" href="https://cdn.jsdelivr.net/npm/cookieconsent@3/build/cookieconsent.min.css" />
+<script src="https://cdn.jsdelivr.net/npm/cookieconsent@3/build/cookieconsent.min.js" data-cfasync="false"></script>
+<script src="https://ropensci.org/scripts/matomo.js"></script>
+<noscript><p><img src="https://ropensci.matomo.cloud/matomo.php?idsite=1&amp;rec=1" style="border:0;" alt="" /></p></noscript>
+<!-- End Matomo Code -->