Improved example for refreshIconOptions
Improved example for refreshIconOptions

Improved clarity of example for `L.Marker.refreshIconOptions` method.
604557209/byzgf,Leaflet/Leaflet.markercluster,frenomus/Leaflet.markercluster,ghybs/Leaflet.markercluster,nerik/Leaflet.markercluster,zverev/Leaflet.markercluster,ghybs/Leaflet.markercluster,Leaflet/Leaflet.markercluster,frenomus/Leaflet.markercluster,604557209/byzgf,zverev/Leaflet.markercluster,nerik/Leaflet.markercluster