Attaches the specified object to the specified index.
See https://www.paws-r-sdk.com/docs/clouddirectory_attach_to_index/ for full documentation.
clouddirectory_attach_to_index(DirectoryArn, IndexReference, TargetReference)
[required] The Amazon Resource Name (ARN) of the directory where the object and index exist.
[required] A reference to the index that you are attaching the object to.
[required] A reference to the object that you are attaching to the index.