Clarification Needed on Custom Configuration Documentation

The [published](https://3b1b.github.io/manim/documentation/custom_config.html) configuration format appears to be outdated and does not accurately reflect the current state of the project's codebase, whether in the latest release [1.7.2](https://github.com/3b1b/manim/blob/f427fc67df75513be0cd3f3329e327a9a19401c3/manimlib/default_config.yml) or the master branch. This discrepancy may prove frustrating for newcomers who might not be aware of this issue.

Additionally, it would be beneficial to improve navigation by cross-linking the GitHub repository and the project website. Including a link to the 'About' section on GitHub and adding a global link from 3b1b.github.io to the GitHub page would enhance user experience.

Compare the published custom configuration page at 3b1b.github.io/manim/documentation/custom_config.html with the actual default_config.yml file in the repository. Identify discrepancies in keys, structure, or descriptions. Also, examine the website's navigation to find where to add links between the GitHub repo and the project site. The work is done when the documentation reflects the current config and cross-links are added.

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