Output size is not part of the argument list

## 📚 Documentation Issue

This issue category is for problems about existing documentation, not for asking how-to questions.

* Provide a link to an existing documentation/comment/tutorial:

https://github.com/facebookresearch/detectron2/blob/5aeb252b194b93dc2879b4ac34bc51a31b5aee13/detectron2/data/transforms/augmentation_impl.py#L471-L480

* How should the above documentation/comment/tutorial improve:

The documentation lists `output_size` as a parameter, however the constructor does not seem to support that value (nor is it used anywhere in the class)