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

<!--- Based on sphinx versionwarning extension. Extension currently only works on READTHEDOCS -->
  <script>
    // 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>');
    }

    // Create a banner if we're not the latest version
    current_url = window.location.href;
    if ((current_url.search("latest") > -1) || (current_url.search("/{{ latest_version }}/") > -1)) {
     // no banner for latest release
    } else if (current_url.search("devel") > -1) {
      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>');
    }
  </script>