comprehensive explanation of metrics, models and dataset

[niansong1996]

Making sure that we have rather comprehensive descriptions/explanations of the metrics, models and datasets.

We should have methods to list all models/datasets/metrics, either in natural language describing them, or using something like prettytable to print tables in the readme to the console/notebook.

[zhangir-azerbayev]

For a long time I've been wanting to write a detailed documentation page using Sphinx. I am swamped for the next week or so, but could start working on it from 10/19 if it sounds like a good idea.