Add analytics block on PyIceberg website (apache#2587)

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Closes apache#2559 

# Rationale for this change
This adds the same Matomo script tag found in the Iceberg website to our
Python documentation website.

## Are these changes tested?
<img width="1670" height="620" alt="Screenshot 2025-10-06 at 3 53 49 PM"
src="https://github.com/user-attachments/assets/18b33bdb-0046-4c11-88da-a006246fab5f"
/>

Script tag found when served locally.

## Are there any user-facing changes?

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Author: rambleraptor

dev/.rat-excludes

@@ -4,3 +4,4 @@ build
 .git
 .gitignore
 poetry.lock
+mkdocs/*

mkdocs/mkdocs.yml

@@ -35,6 +35,7 @@ plugins:
 
 theme:
   name: material
+  custom_dir: overrides
   logo: assets/images/iceberg-logo-icon.png
   favicon: assets/images/iceberg-logo-icon.png
   font:

mkdocs/overrides/main.html

@@ -0,0 +1,22 @@
+{% extends "base.html" %}
+
+{% block extrahead %}
+  {{ super() }}
+  <!-- Matomo -->
+  <script>
+    var _paq = window._paq = window._paq || [];
+    /* tracker methods like "setCustomDimension" should be called before "trackPageView" */
+    _paq.push(["setDoNotTrack", true]);
+    _paq.push(["disableCookies"]);
+    _paq.push(['trackPageView']);
+    _paq.push(['enableLinkTracking']);
+    (function() {
+      var u="https://analytics.apache.org/";
+      _paq.push(['setTrackerUrl', u+'matomo.php']);
+      _paq.push(['setSiteId', '82']);
+      var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
+      g.async=true; g.src=u+'matomo.js'; s.parentNode.insertBefore(g,s);
+    })();
+  </script>
+  <!-- End Matomo -->
+{% endblock %}