Wrong documentation for addition/subtraction matrix+scalar (maths.md)

[adria-p]

More concretely, I believe that the following is not correct:

The scalar might be on the right or left of the operator.

And then also the last example will fail:

> = 3-x

 1  1
 1  1
[torch.Tensor of dimension 2x2]

[soumith]

that sounds right, it should be -x + 3
let me correct that.