Updated options.md with visibleMarkersList
Updated options.md with visibleMarkersList

EdwardPantoja/jQuery-Store-Locator-Plugin,heatery/jQuery-Store-Locator-Plugin,bjorn2404/jQuery-Store-Locator-Plugin,bjorn2404/jQuery-Store-Locator-Plugin,heatery/jQuery-Store-Locator-Plugin,EdwardPantoja/jQuery-Store-Locator-Plugin,heatery/jQuery-Store-Locator-Plugin,EdwardPantoja/jQuery-Store-Locator-Plugin