message: Add more words to doc
  Summary: Fix T43078
  Reviewers: jakeh, #tensorflow, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, markf
  Subscribers: markf
  Maniphest Tasks: T43078
diff: @@ -135,10 +135,11 @@ class IPUInfeedQueue:
  prefetch_depth: the number of elements Poplar will prefetch.
  The depth of the Poplar datastream buffer size which may be prefetched
  before being read by the device. By default the prefetch_depth size is
  - automatically determined. Increasing the size of the prefetch_depth
  - allows for prefetching of multiple entries, increasing the probability
  - there will be a valid entry in the buffer for the device to read
  - before falling back to synchronously fetching the next entry.
  + automatically determined (currently defaults to 1). Increasing the size
  + of the prefetch_depth allows for prefetching of multiple entries,
  + increasing the probability there will be a valid entry in the buffer for
  + the device to read before falling back to synchronously fetching the
  + next entry. This value has to be greater than zero.
  Raises:
  ValueError: if all dimensions of shapes of dataset.output_shapes are not
  