code: public function addCustomLayoutSectionReferences()
  	{
  		$objLayout = $this->Database->getInstance()->query("SELECT sections FROM tl_layout WHERE sections!=''");
  
  		while ($objLayout->next())
  		{
  			$arrCustom = StringUtil::deserialize($objLayout->sections);
  
  			// Add the custom layout sections
  			if (!empty($arrCustom) && \is_array($arrCustom))
  			{
  				foreach ($arrCustom as $v)
  				{
  					if (!empty($v['id']))
  					{
  						$GLOBALS['TL_LANG']['COLS'][$v['id']] = $v['title'];
  					}
  				}
  			}
  		}
  	}
docs: Add the custom layout section references