Defining quick actions in the backend main navigation

To define quick actions in the main navigation, you need to add this method to the Plugin.php file:

public function registerQuickActions()
{
    return [
        'help' => [
            'label' => 'Read the documentation',
            'icon' => 'icon-question-circle',
            'url' => Backend::url('read-the-docs'),
        ],
        'mail' => [
            'label' => 'Send email to developers',
                        // SVG-icon example
            'iconSvg' => '/plugins/sandbox/quickactions/assets/svg/mail.svg',
            'url' => Backend::url('mail-to-devs'),
        ],           
    ];
}

Works with the latest version of OctoberCms installed via composer.