It's built in the DocetManager#servePageIdForLanguageForPackage that when you serve a html/pdf page you never include what is inside the head of the document and some tags are cleaned (like Githubissues.
Githubissues is a development platform for aggregating issues.
In this pull request I introduced a meta tag
To skip the TOC unlinked file validation. Writing the head tag with inside this meta you can still pass the validation of the documentation page.