[BUG] Trirank documentation X&Y

[linan1109]

For model.Triank, the document says X is for user-aspect and Y is for item-aspect.

But in the code, it should be the other way round, i.e. X for item-aspect and Y for user-aspect.

[qtuantruong]

@lthoang is it something to be corrected?

[lthoang]

Based on the original paper, the code is correct. I made a mistake in the model's documentation.

So we have to update the documentation accordingly.

@linan1109 Thank you for pointing out this error.