Document difference between *Hparams and associated class

[growlix]

We should explicitly describe the difference between usage scenarios for Hparams objects vs the classes they end up instantiating (e.g. TQDMLogger vs. TQDMLoggerHparams). I think the right place to do this is probably in every *Hparams docstring. I am thinking something like:

*Hparams is used to instantiate * via YAML configs instead of calling it directly.

but I might be missing something because I'm not an expert.

[ravi-mosaicml]

Need to add a YAHP tutorial, and then we can link in each docstring to the yahp tutorial.

[mvpatel2000]

YAHP is gone :)