ansible/docs/docsite/_themes/sphinx_rtd_theme/ansible_banner.html

<!--- Based on sphinx versionwarning extension. Extension currently only works on READTHEDOCS -->
  <script>
    startsWith = function(str, needle) {
      return str.slice(0, needle.length) == needle
    }
    // Create a banner if we're not on the official docs site
    if (location.host == "docs.testing.ansible.com") {
      document.write('<div id="testing_banner_id" class="admonition important">');
      para = document.createElement('p');
      banner_text=document.createTextNode("This is a testing site. For the official docs go to https://docs.ansible.com/");
      para.appendChild(banner_text);
      element = document.getElementById('testing_banner_id');
      element.appendChild(para);
      document.write('</div>');
    }
    {% if (not READTHEDOCS) and (available_versions is defined) %}
      // Create a banner if we're not the latest version
      current_url_path = window.location.pathname;
      if (startsWith(current_url_path, "/ansible/latest/") || startsWith(current_url_path, "/ansible/{{ latest_version }}/")) {
       // no banner for latest release
      } else if (startsWith(current_url_path, "/ansible/devel/")) {
        document.write('<div id="banner_id" class="admonition caution">');
        para = document.createElement('p');
        banner_text=document.createTextNode("You are reading the *devel* version of the Ansible documentation - this version is not guaranteed stable. Use the version selection to the left if you want the latest stable released version.");
        para.appendChild(banner_text);
        element = document.getElementById('banner_id');
        element.appendChild(para);
        document.write('</div>');
      } else {
        document.write('<div id="banner_id" class="admonition caution">');
        para = document.createElement('p');
        banner_text=document.createTextNode("You are reading an older version of the Ansible documentation. Use the version selection to the left if you want the latest stable released version.");
        para.appendChild(banner_text);
        element = document.getElementById('banner_id');
        element.appendChild(para);
        document.write('</div>');
      }
    {% endif %}
  </script>