Docstring Style Standardization

[AndrewSazonov]

This ADR standardizes docstrings to use the NumPy-style.

The decision is based on a comparison of the three main docstring styles currently relevant to our tooling and documentation workflow: Sphinx-style, Google-style, and NumPy-style. All three styles are supported by our documentation build tools (MkDocs + mkdocstrings) and produce equivalent user-facing API reference documentation. Therefore, the main differences is in developer experience and tooling support.

To help with converting existing docstrings to the selected style, the Python tool docstripy can be used. It is currently included in our template system.

NumPy-style example:

"""
Insert an object into the collection at an index.

Parameters
----------
index : int
    Index for EasyScience object to be inserted.
value : Union[BasedBase, DescriptorBase, NewBase]
    Object to be inserted.

Returns
-------
None
"""

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Links to the related discussions: #66