Add Plausible for docs metrics (#119977)

Co-authored-by: Julien Palard <[email protected]>

Doc/conf.py

@@ -339,7 +339,8 @@
 html_context = {
     "is_deployment_preview": os.getenv("READTHEDOCS_VERSION_TYPE") == "external",
     "repository_url": repository_url.removesuffix(".git") if repository_url else None,
-    "pr_id": os.getenv("READTHEDOCS_VERSION")
+    "pr_id": os.getenv("READTHEDOCS_VERSION"),
+    "enable_analytics": os.getenv("PYTHON_DOCS_ENABLE_ANALYTICS"),
 }
 
 # This 'Last updated on:' timestamp is inserted at the bottom of every page.

Doc/tools/templates/layout.html

@@ -26,6 +26,9 @@
 {% endblock %}
 
 {% block extrahead %}
+    {% if builder == "html" and enable_analytics %}
+      <script defer data-domain="docs.python.org" src="https://plausible.io/js/script.js"></script>
+    {% endif %}
     <link rel="canonical" href="https://docs.python.org/3/{{pagename}}.html" />
     {% if builder != "htmlhelp" %}
       {% if pagename == 'whatsnew/changelog' and not embedded %}