Restricted Branch - documents to be hidden for viewers

Hi GitHub Support,

I’m currently using my company’s enterprise GitHub and have a quick question. We have three roles in GitHub: read-only, developer, build manager. However it’s come to our attention that we can’t show some of our documents to the read-only viewers. Is there anyway we can do that? I was thinking about having a restricted branch where we put these docs so that they don’t get shown to the viewers. Would it be possible? My colleague told me it’s not possible. Appreciate your confirm and advice.

Many thanks,
Christine