enhance_github pages doc (AtsushiSakai#673)

Author: AtsushiSakai

docs/_templates/layout.html

@@ -6,3 +6,19 @@
         src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-9612347954373886"
         crossOrigin="anonymous"></script>
 {% endblock %}
+
+{% block sidebarsearch %}
+{{ super() }}
+<script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-9612347954373886"
+     crossorigin="anonymous"></script>
+<!-- PythonRoboticsDoc -->
+<ins class="adsbygoogle"
+     style="display:block"
+     data-ad-client="ca-pub-9612347954373886"
+     data-ad-slot="1579532132"
+     data-ad-format="auto"
+     data-full-width-responsive="true"></ins>
+<script>
+     (adsbygoogle = window.adsbygoogle || []).push({});
+</script>
+{% endblock %}