Improved readability, grammar, as well as added docstrings for consistency

[NASAnerd05]

…py readability and docstrings

Overview: What does this pull request change?

This PR includes:

• Fixes for minor grammar mistakes in .rst files under docs/source
• Docstrings added to classes that were previously missing them (for consistency)
• Readability improvements to some existing docstrings
• File-level docstrings added to a few .py files to help quickly identify their purpose

Motivation and Explanation: Why and how do your changes improve the library?

These changes improve the overall readability and consistency of the documentation and source files. While they don't affect functionality, they help make the codebase a little easier to navigate and understand — especially for new contributors or users exploring the internals.

Links to added or changed documentation pages

https://manimce--4267.org.readthedocs.build/en/4267/

Further Information and Comments

Thank you for the opportunity to contribute! Let me know if there's anything I should do differently, especially formatting-wise or regarding documentation style. I'm here to learn.

Reviewer Checklist

• The PR title is descriptive enough for the changelog, and the PR is labeled correctly
• If applicable: newly added non-private functions and classes have a docstring including a short summary and a PARAMETERS section
• If applicable: newly added functions and classes are tested