charlie: Documentation Update

[shellscape]

Please examine the current state of the code and examine all of the markdown files in the docs directory. A quick examination was done in this comment https://github.com/shellscape/postcss-values-parser/issues/152#issuecomment-3480873690 but it is not comprehensive. Please look for an identify any and all discrepancies, including those pointed out in that Github comment. Open a PR to resolve any issues with the documentation that are found.