adds leaflet-solr-heatmap to plugin directory (#5707)
adds leaflet-solr-heatmap to plugin directory (#5707)


scaddenp/Leaflet,Leaflet/Leaflet,Leaflet/Leaflet,msiadak/Leaflet,scaddenp/Leaflet,CapeSepias/Leaflet,msiadak/Leaflet,stefanocudini/Leaflet,CapeSepias/Leaflet,geoloep/Leaflet,scaddenp/Leaflet,stefanocudini/Leaflet,msiadak/Leaflet,geoloep/Leaflet,geoloep/Leaflet,Leaflet/Leaflet,CapeSepias/Leaflet,stefanocudini/Leaflet