adding clear docs in the example notebook for multi selector
adding clear docs in the example notebook for multi selector

dmadeka/bqplot,bloomberg/bqplot,bloomberg/bqplot,bloomberg/bqplot,ssunkara1/bqplot,SylvainCorlay/bqplot,ChakriCherukuri/bqplot,ChakriCherukuri/bqplot,dmadeka/bqplot,SylvainCorlay/bqplot,ssunkara1/bqplot,ChakriCherukuri/bqplot,SylvainCorlay/bqplot