message: Improve API documentation for WindowDataset op
diff: @@ -4,29 +4,54 @@ op {
  in_arg {
  name: "size"
  description: <<END
  -A scalar representing the number of elements to accumulate in a window.
  +A scalar representing the number of elements to accumulate in a window. It must
  +be positive.
  END
  }
  in_arg {
  name: "shift"
  description: <<END
  -A scalar representing the steps moving the sliding window forward in one
  -iteration. It must be positive.
  +A scalar representing the number of input elements by which the window moves
  +on each iteration. It must be positive.
  END
  }
  in_arg {
  name: "stride"
  description: <<END
  A scalar representing the stride of the input elements of the sliding window.
  -It must be positive.
  +It must be positive. A value of 1 means "retain every input element".
  END
  }
  in_arg {
  name: "drop_remainder"
  description: <<END
  -A scalar representing whether a window should be dropped in case its size is
  -smaller than desired.
  +A scalar representing whether the last window in the dataset should be dropped
  +if its size is smaller than the value of `size`.
  END
  }
  - summary: "A dataset that creates window datasets from the input dataset."
  + summary: <<END
  + A dataset that groups the elements of its input dataset into fixed-sized
  + windows. Each window is returned as a separate dataset object.
  +
  + The first element in the `k`th window will be element
  + ```
  + 1 + (k-1) * shift
  + ```
  + of the input dataset. In particular, the first element of the first window
  + will always be the first element of the input dataset.
  +
  + If the `stride` parameter is greater than 1, then each window will skip
  + `(stride - 1)` input elements between each element that appears in the
  + window. Output windows will still contain `size` elements regardless of
  + the value of `stride`.
  +
  + If the underlying dataset returns elements in a deterministic order, then the
  + output of `WindowDataset` will be deterministic. Otherwise, the output of
  + this dataset will depend on the input order, but the contents of the windows
  + will be consistent with a single ordering of the input dataset's elements.
  +
  + If the input dataset contains multiple tensors per element, this dataset will
  + return multiple datasets for each window. Each returned dataset will
  + correspond to a single window of one of the tensors in the input dataset.
  +END
  }
  