README.md is not up-to-date

[cb2004]

I found these options in MarkupGoogleMap.module but they are not in the actual README.md so can easily be missed:

 * // use hover box? When true, shows a tooltip-type box when you hover the marker, populated with the markerTitleField
 * // this is often more useful than the default presentation google maps uses
 * 'useHoverBox' => false
 *
 * // when useHoverBox is true, you can specify the markup used for it. Use the following (which is the default) as your starting point:
 * 'hoverBoxMarkup' => "<div data-top='-10' data-left='15' style='background: #000; color: #fff; padding: 0.25em 0.5em; border-radius: 3px;'></div>", 
 *
 * // FUll URL to icon file to use for markers. Blank=use default Google marker icon. 
 * 'icon' => '', 
 * 
 * // Any extra javascript initialization code you want to occur before the map itself is drawn
 * 'init' => '',