text: Title: Change docstring style to google-style
  Body: Right now there is numpy-style in docstring. Please change to google-style (https://sphinxcontrib-napoleon.readthedocs.io/en/latest/example_google.html) because I would like to integrate this doc with mkdocs-material and the only reasonable package to do this in automated way (mkdocstrings) works only with google-style docstring.