deploying "EXTRA_FILES" needs to be explained better

The deploy subcommands take "EXTRA_FILES" arguments, but it's really unclear how it actually works.

The --help shows:

rsconnect deploy api [OPTIONS] DIRECTORY [EXTRA_FILES]...

And the README shows:

rsconnect deploy api flask-api/ data.csv

But when I try it (eg rsconnect deploy api ./hello/ data.txt), I get an error:

Error: ../data.txt must be under ./hello/.

So I need to have data.txt inside the hello directory? Doesn't everything inside the app directory get included by default? What's the point of EXTRA_FILES then? Is it just to negate a --exclude, as described in the README? What am I missing?

Also, the documentation should clearly state where the extra files get placed inside the app directory hierarchy. One would assume they get placed in the root but why make people guess? The documentation should be more clear.

Start with the README deploy examples and the deploy subcommands' --help output, then trace where EXTRA_FILES is described. Clarify when extra files are included, how they relate to --exclude, and where they appear in the app directory hierarchy; done means the documented behavior answers the reported questions without guesswork.