Update Readme to mention animateAddingMarkers doesn't work with addLayers
Update Readme to mention animateAddingMarkers doesn't work with addLayers

Thanks @Driklyn
mr47/Leaflet.markercluster,cyrilchaponeverysens/Leaflet.markercluster,alex2wong/Leaflet.markercluster,MazeMap/Leaflet.markercluster,zverev/Leaflet.markercluster,MazeMap/Leaflet.markercluster,Leaflet/Leaflet.markercluster,radnor/Leaflet.markercluster,604557209/byzgf,mr47/Leaflet.markercluster,hoganmaps/Leaflet.markercluster,tobias-johansson/Leaflet.markercluster,nerik/Leaflet.markercluster,VincentDS/Leaflet.markercluster,meboban/Leaflet.markercluster,hoganmaps/Leaflet.markercluster,lrpauley/Leaflet.markercluster,Leaflet/Leaflet.markercluster,tobias-johansson/Leaflet.markercluster,ghybs/Leaflet.markercluster,604557209/byzgf,paulserraino/leaflet-geojson-cluster,VincentDS/Leaflet.markercluster,frenomus/Leaflet.markercluster,lrpauley/Leaflet.markercluster,alex2wong/Leaflet.markercluster,paulserraino/leaflet-geojson-cluster,Intermaps/Leaflet.markercluster,zoutepopcorn/Leaflet.markercluster,zverev/Leaflet.markercluster,radnor/Leaflet.markercluster,cyrilchaponeverysens/Leaflet.markercluster,meboban/Leaflet.markercluster,Chuck8080/web-maps-markercluster,frenomus/Leaflet.markercluster,zoutepopcorn/Leaflet.markercluster,Intermaps/Leaflet.markercluster,nerik/Leaflet.markercluster,ghybs/Leaflet.markercluster