docs: add Google Analytics 4 tracking script via head_custom.html

Author: bsayli

docs/_config.yml

@@ -3,7 +3,6 @@ description: Type-safe OpenAPI clients with generics (Spring Boot + OpenAPI Gene
 
 just_the_docs:
   custom_css: assets/css/custom.css
-  ga_measurement_id: G-HMPG85XV29
 
 remote_theme: just-the-docs/just-the-docs
 

docs/_includes/head_custom.html

@@ -0,0 +1,8 @@
+<!-- Google Analytics 4 -->
+<script async src="https://www.googletagmanager.com/gtag/js?id=G-HMPG85XV29"></script>
+<script>
+    window.dataLayer = window.dataLayer || [];
+    function gtag(){dataLayer.push(arguments);}
+    gtag('js', new Date());
+    gtag('config', 'G-HMPG85XV29');
+</script>