message: correct description of bounding box points
  points are upperleft and bottomright not bottomleft and upperright. Also coordinates were in idiosyncratic (y,x) instead of (x,y) form. And no, those two corrections don't cancel.
diff: @@ -705,9 +705,9 @@ bounding box in `boxes` are encoded as `[y_min, x_min, y_max, x_max]`. The
  bounding box coordinates are floats in `[0.0, 1.0]` relative to the width and
  height of the underlying image.
  -For example, if an image is 100 x 200 pixels and the bounding box is
  -`[0.1, 0.2, 0.5, 0.9]`, the bottom-left and upper-right coordinates of the
  -bounding box will be `(10, 40)` to `(50, 180)`.
  +For example, if an image is 100 x 200 pixels (height x width) and the bounding
  +box is `[0.1, 0.2, 0.5, 0.9]`, the upper-left and bottom-right coordinates of
  +the bounding box will be `(40, 10)` to `(100, 50)` (in (x,y) coordinates).
  Parts of the bounding box may fall outside the image.
  