Examples in the documentation should be elaborated more

[JaeyeongYang]

As ADOpy includes several implementations for specific tasks and models, it would be great to include detailed examples for these implementations. However, the current examples somewhat lack descriptions in plain English.

The example files should be included in /docs/source/examples as Jupyter notebook files. If the notebook file is properly executed, it can be automatically integrated into the Sphinx-based documentation (based on nbsphinx).