[docs] DM-5427 Google Tag Manager setup for analytics in our docs

Author: joffrey-bion

docs/mkdocs.yml

@@ -14,6 +14,7 @@ docs_dir: src
 
 theme:
   name: material
+  custom_dir: overrides
   logo: images/amper-icon.svg
   favicon: images/amper-icon.svg
   icon:
@@ -103,6 +104,7 @@ markdown_extensions:
 watch:
   - .icons
   - includes
+  - overrides
 
 nav:
   - 'Home': index.md

docs/overrides/main.html

@@ -0,0 +1,21 @@
+{% extends "base.html" %}
+
+{% block analytics %}
+<!-- Google Tag Manager -->
+<script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
+        new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
+    j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
+    'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
+})(window,document,'script','dataLayer','GTM-5P98');</script>
+<!-- End Google Tag Manager -->
+
+{% endblock %}
+
+{% block header %}
+<!-- Google Tag Manager (noscript) -->
+<noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-5P98"
+                  height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript>
+<!-- End Google Tag Manager (noscript) -->
+
+{{ super() }}
+{% endblock %}