[Plugin:Availability Calendar] Editing code to alter permissions

Hi, I’ve installed the availability calendar to a website without problem. I would like to modify the code slightly to allow users ranked as either ‘administrator’ or ‘editor’ to have access to the calendar booking admin panel. I’m no good at PHP, so a little advice would be appreciated.

Simply swapping ‘administrator’ in this code for ‘editor’ allows editor access. How do I change this code to display the menu for both users?

function admin_menu()
		{
			add_submenu_page(
				'edit-pages.php',
				'Manage '.$this->name,
				$this->name,
				'administrator',
				$this->tag,
				array(&$this, 'manage')
			);
		}

Site here; http://stayincostaesuri.com.

Many thanks