[suggestion] Add a parameter description to some main methods

[DragonBoard]

Suggest to add a parameter description to some main methods ( such as basemodel.fit ( ) and some models ) to facilitate the user to read the code. Can refer to the https://github.com/shenweichen/DeepCTR-Torch parameter annotations and documentation.
I hope more comments to facilitate reading code.

[xpai]

Thanks for your suggestion! Yes, the documentation of FuxiCTR is missing now. It needs a large effort to make it. We welcome any contribution for this.