Ship google analytics javascript in head.hbs

Upstream mdbook deprecates its included google analytics in order not
to prefer one analytics engine over all others.

Part of #77

Signed-off-by: Klaus Kämpf <kkaempf@suse.de>

book.toml

@@ -12,4 +12,3 @@ git-repository-url = "https://github.com/kubewarden/docs"
 edit-url-template = "https://github.com/kubewarden/docs/edit/main/{path}"
 site-url = "/"
 cname = "docs.kubewarden.io"
-google-analytics = "UA-56382716-13"

theme/head.hbs

@@ -0,0 +1,11 @@
+{{!-- Put your head HTML text here --}}
+<script type="text/javascript">
+(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
+(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new
+Date();a=s.createElement(o),
+m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
+})(window,document,'script','https://www.google-analytics.com/analytics.js','ga');
+ga('set','anonymizeIp',!0);
+ga('create', 'UA-56382716-13', 'auto');
+ga('send', 'pageview');
+</script>