Searching in a subdirectory of org-dir

I am trying to use this package to query files in a `notes` directory that is below my org directory. `org-ql-search` makes it possible to interactively target the org directory, but it doesn't seem to search recursively in subdirectories. How can I conveniently target this subdirectory `org/notes`?

I noticed that in the README documentation for `org-ql-search` it says you can provide any expression that resolves to a list of files. It seems cumbersome to write an expression here. I could define a custom function I suppose. But I'm wondering if there's a suggested solution for this scenario which seems like it might crop up frequently.