Add Matomo tracking code via static JavaScript file

docs/source/_static/matomo.js

@@ -0,0 +1,14 @@
+// script below is used by Matomo web analytics for web site usage statistics
+<script>
+  var _paq = window._paq = window._paq || [];
+  /* tracker methods like "setCustomDimension" should be called before "trackPageView" */
+  _paq.push(['trackPageView']);
+  _paq.push(['enableLinkTracking']);
+  (function() {
+    var u="https://openms.matomo.cloud/";
+    _paq.push(['setTrackerUrl', u+'matomo.php']);
+    _paq.push(['setSiteId', '3']);
+    var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
+    g.async=true; g.src='https://cdn.matomo.cloud/openms.matomo.cloud/matomo.js'; s.parentNode.insertBefore(g,s);
+  })();
+</script>

docs/source/conf.py

@@ -187,7 +187,7 @@
 html_static_path = ["_static"]
 html_css_files = ["custom.css"]
 # adding custom icons probably only possible with newest pydata theme version
-html_js_files = ["piwik.js", "custom.js"] #, "custom_icon.js"]
+html_js_files = ["piwik.js", "matomo.js", "custom.js"]
 
 # -- Options for HTMLHelp output ------------------------------------------