reword parallel execution description for Dataset (#3217)

Co-authored-by: Vasilis Vryniotis <datumbox@users.noreply.github.com>

docs/source/datasets.rst

@@ -4,7 +4,7 @@ torchvision.datasets
 All datasets are subclasses of :class:`torch.utils.data.Dataset`
 i.e, they have ``__getitem__`` and ``__len__`` methods implemented.
 Hence, they can all be passed to a :class:`torch.utils.data.DataLoader`
-which can load multiple samples parallelly using ``torch.multiprocessing`` workers.
+which can load multiple samples in parallel using ``torch.multiprocessing`` workers.
 For example: ::
 
     imagenet_data = torchvision.datasets.ImageNet('path/to/imagenet_root/')