Add Docstring and enhance readme file in Chess Game project

[Gabriela20103967]

Description

In this issue I want to add docstrings to the function in the two existing modules of the Chess Game project to have a clear and well documented code to help us to understand it better, also update the README file with more information about the game that can help to understand a little bit more and have for information of the game.

Type of issue

• Feature (New Script)
• Bug
• Documentation

Checklist:

• I have read the project guidelines.
• I have checked previous issues to avoid duplicates.
• This issue will be meaningful for the project.