Linting: Make sure the sidebar links actually exist in the filesystem #8234
Description
In #8221 I deleted a bunch of old v5 migration/upgrade guides and created new cake 6 docs.
BUT I forgot to adjust the toc_en.json so the sidebar does not reflect that change.
It would be cool if there is a CI step which makes sure, that all the links mentioned in the toc_<lang>.json file actually exist.