Fix the document of buffer_size in max_token_bucketize (pytorch#834)

Summary:
This PR would fix a document issue in bucketbatcher.py
Fixes pytorch#831

Pull Request resolved: pytorch#834

Reviewed By: NivekT

Differential Revision: D40430887

Pulled By: ejguan

fbshipit-source-id: e132a3a24e8d09815c36bba3ccd4ffaced7b17d4

torchdata/datapipes/iter/transform/bucketbatcher.py

@@ -220,7 +220,7 @@ class MaxTokenBucketizerIterDataPipe(IterDataPipe[DataChunk[T_co]]):
         len_fn: Function to be applied to each element to get lengths. ``len(data)`` is used by default.
         min_len: Optional minimum length to be included into each batch
         max_len: Optional maximum length to be included into each batch.
-        buffer_size: This restricts how many tokens are taken from prior DataPipe to bucketize
+        buffer_size: This restricts how many samples are taken from prior DataPipe to bucketize
         include_padding: If True, the size of each batch includes the extra padding to the largest length in the batch.
 
     Example: