typo fix

  >>> smiles = ["C", "CCC"]

  >>> featurizer=dc.feat.ConvMolFeaturizer(per_atom_fragmentation=False)

  >>> f = featurizer.featurize(smiles)

  Using ConvMolFeaturizer to create featurized fragments derived from molecules of interest.

  This is used only in the context of performing interpretation of models using atomic

  contributions (atom-based model interpretation)

  >>> import deepchem as dc

  >>> smiles = ["C", "CCC"]

  >>> # Using ConvMolFeaturizer to create featurized fragments derived from molecules of interest.

  ... # This is used only in the context of performing interpretation of models using atomic

  ... # contributions (atom-based model interpretation)

  ... smiles = ["C", "CCC"]

  >>> featurizer=dc.feat.ConvMolFeaturizer(per_atom_fragmentation=True)

  >>> f = featurizer.featurize(smiles)

  >>> len(f) # contains 2 lists with  featurized fragments from 2 mols