Fix typo in Dask Bag docs  [ci skip] (#3319)
Fix typo in Dask Bag docs  [ci skip] (#3319)


jakirkham/dask,jcrist/dask,mrocklin/dask,blaze/dask,blaze/dask,ContinuumIO/dask,dask/dask,ContinuumIO/dask,dask/dask,mrocklin/dask,jcrist/dask,jakirkham/dask