Fix typo in sample usage

[gteufelberger]

height was typoed to hieght.

This means when trying to run the sample code one would get:

---------------------------------------------------------------------------

TypeError                                 Traceback (most recent call last)

[<ipython-input-15-0aa60d9f7322>](https://localhost:8080/#) in <module>
      1 from DiffJPEG import DiffJPEG
----> 2 jpeg = DiffJPEG(hieght=224, width=224, differentiable=True, quality=80)
      3 
      4 class PGD_JPEG(attacks.PGD):
      5     """

TypeError: __init__() got an unexpected keyword argument 'hieght'