[feature]: filter_nav but to hide files which are built

[NyaomiDEV]

🚀 Feature description

filter_nav_tag (array of strings) to filter out Markdown pages which have select tags, but only from navigation (eg. actually render them, but have them hidden). This behaviour should only be applied if filter_nav: true.

🔈 Motivation

Subpages that should not be rendered in navigation to prevent clutter. Or easter eggs. Or "private-ish" pages.

🛰 Alternatives

Defining nav by myself: Tedious, manual, not really feasible if I just want to work on the documentation contents.
awesome-pages: Less manual, but still it can only filter out entire directories and not single files.

📎 Additional context

Not really applicable, I outlined the context on the motivation section.

📜 Code of Conduct

• I agree to follow this project's Code of Conduct.