docs: show link to latest version

Author: makkus

docs/.overrides/main.html

@@ -0,0 +1,8 @@
+{% extends "base.html" %}
+
+{% block outdated %}
+  You're not viewing the latest version.
+  <a href="{{ '../' ~ base_url }}">
+    <strong>Click here to go to latest.</strong>
+  </a>
+{% endblock %}