I used the Custom CSS app to add the following CSS to my Nextcloud site:
#filelist-header #rich-workspace {
display:none;
}
I also filed bug report #586 in GitHub. I’m not happy that this feature was built-in to the Text app; this feature was enabled by default; and there was no documentation for it. Even though this thread showed me how to shut it off, I’ll keep my custom CSS in place to make sure my server’s folders don’t get filled up with empty README.md files.