update KeyboardHelpDialog to have only 1 aria-labelledby attribute for title, https://github.com/phetsims/scenery-phet/issues/494
update KeyboardHelpDialog to have only 1 aria-labelledby attribute for title, https://github.com/phetsims/scenery-phet/issues/494

phetsims/sun,phetsims/sun,phetsims/sun