what if we want to exclude md files from being built by mkdocs if they are not listed in literate-nav file?

## Feature request

I'd like the ability to let literate nav remove articles from being built (e.g. turned into html files and included in the generated `site/`) if those articles are not in the `SUMMARY.md` nav file.

There might even already be a way to do this. If there is could you let me know?

Thanks again for the awesome plugin! 👏🏼 