[WIP] Fix access issue for document pages

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

Open the following pages and summarize their contents:

https://docs.coveo.com/en/llms.txt
https://docs.coveo.com/en/llms-full.txt
https://docs.coveo.com/en/1373.md
https://docs.coveo.com/en/1372

If you can't access them, tell me why. Debug it.

Tell me what's their relationship to this headless-documentation-material-ui-react-codesandbox repository.

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