text: Title: `train` parameter should be explained before `download`, `transform` and `target_transform` parameter
  Body: ### 📚 The doc issue
  
  In [the doc](https://pytorch.org/vision/stable/generated/torchvision.datasets.QMNIST.html) of `QMNIST()`, `train` parameter is located before `**kwargs` which are `download`, `transform` and `target_transform` parameter as shown below:
  
  > class torchvision.datasets.QMNIST(root: [Union](https://docs.python.org/3/library/typing.html#typing.Union)[[str](https://docs.python.org/3/library/stdtypes.html#str), [Path](https://docs.python.org/3/library/pathlib.html#pathlib.Path)], what: [Optional](https://docs.python.org/3/library/typing.html#typing.Optional)[[str](https://docs.python.org/3/library/stdtypes.html#str)] = None, compat: [bool](https://docs.python.org/3/library/functions.html#bool) = True, train: [bool](https://docs.python.org/3/library/functions.html#bool) = True, **kwargs: [Any](https://docs.python.org/3/library/typing.html#typing.Any))
  
  But `train` parameter is explained after `download`, `transform` and `target_transform` parameter as shown below:
  
  > Parameters:
  > ...
  > - compat ([bool](https://docs.python.org/3/library/functions.html#bool),optional) – A boolean that says whether the target for each example is class number (for compatibility with the MNIST dataloader) or a torch vector containing the full qmnist information. Default=True.
  > - download ([bool](https://docs.python.org/3/library/functions.html#bool), optional) – If True, downloads the dataset from the internet and puts it in root directory. If dataset is already downloaded, it is not downloaded again.
  > - transform (callable, optional) – A function/transform that takes in a PIL image and returns a transformed version. E.g, transforms.RandomCrop
  > - target_transform (callable, optional) – A function/transform that takes in the target and transforms it.
  > - train ([bool](https://docs.python.org/3/library/functions.html#bool),optional,compatibility) – When argument ‘what’ is not specified, this boolean decides whether to load the training set or the testing set. Default: True.
  
  ### Suggest a potential alternative/fix
  
  So, `train` parameter should be explained before `download`, `transform` and `target_transform` parameter as shown below:
  
  > Parameters:
  > ...
  > - compat ([bool](https://docs.python.org/3/library/functions.html#bool),optional) – A boolean that says whether the target for each example is class number (for compatibility with the MNIST dataloader) or a torch vector containing the full qmnist information. Default=True.
  > - train ([bool](https://docs.python.org/3/library/functions.html#bool),optional,compatibility) – When argument ‘what’ is not specified, this boolean decides whether to load the training set or the testing set. Default: True.
  > - download ([bool](https://docs.python.org/3/library/functions.html#bool), optional) – If True, downloads the dataset from the internet and puts it in root directory. If dataset is already downloaded, it is not downloaded again.
  > - transform (callable, optional) – A function/transform that takes in a PIL image and returns a transformed version. E.g, transforms.RandomCrop
  > - target_transform (callable, optional) – A function/transform that takes in the target and transforms it.