This documentation is not using the current rendering mechanism and is probably outdated. The extension maintainer should switch to the new system. Details on how to use the rendering mechanism can be found here.

Some extra fun!ΒΆ

As a bonus there is some configuration for the top-left logo in the backend, the logo above the backend login form and extra CSS for the login form (which is far from perfect, but enough for a demonstration.

$relativePath = \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::extRelPath($_EXTKEY);
$GLOBALS['TBE_STYLES']['logo_login'] = $relativePath . 'Resources/Public/Backend/Images/LogoLogin.png';
$GLOBALS['TBE_STYLES']['logo'] = $relativePath . 'Resources/Public/Backend/Images/typo3-topbar@2x.png';
$GLOBALS['TBE_STYLES']['inDocStyles_TBEstyle'] .= '
#t3-login-form:after {
  content: "\00a0";
  background-image: url("' . \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::extRelPath($_EXTKEY) . 'Resources/Public/Backend/Images/peeking.png");
  width: 220px;
  height: 187px;
  display: inline-block;
  overflow: hidden;
  position: relative;
  left: 201px;
  bottom: 533px;