W1D3, tut 1 and 2, erroneous doc string

[palec87]

docstring of the init() method of the Net(nn.Module) class says:

"hidden_unit_nums: int Number of units in the hidden layer"

suggested correction: "hidden_unit_nums: list[int] Number of units per hidden layer"

Class used in both tutorials.

[spirosChv]

@palec87 this issue refers to W1D3 of the deep learning course.