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The [published](https://3b1b.github.io/manim/documentation/custom_config.html) configuration format appears to be outdated and does not accurately reflect the current state of the project's codebase, whether in the latest release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.