Remove outdated FAQ page from docs (#3683) [ci skip]

The FAQ page was already left out of the index / nav bar, but
could still be found wiht the search bar. In a discussion in
this PR (#3683),
Paolo decided it's better to leave it in the GitHub Discussions
instead of the docs.

Signed-off-by: Marcel Ribeiro-Dantas <[email protected]>

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Signed-off-by: Marcel Ribeiro-Dantas <[email protected]>