Add descriptions for the params in the config YAML file of MolMIM

[xinyu-dev]

This request is not specifically to MolMIM, but I just use it as an example. It would be very useful to have a a list of descriptions for the params in the YAML file. I can see explanation of a few params the docs, and some in the NeMo repository, but it is scattered and many params aren't easily understood unless digging/asking around. Please consider adding this feature.

Thanks!