Relative file paths are resolved from the wrong path

[LPGhatguy]

First off, thanks for the great tool! It's, at the very least, a great holdover until the external_doc feature stabilizes.

I'm working on a project that's a Cargo workspace, so the root of my repository contains my README.md and only a virtual manifest.

If I run cargo-readme in my project root, I get an error hinting that there's no [package] section in my Cargo.toml:

$ cargo readme -o README.md
Error: missing field `package`

I noticed that the -r flag lets me set the project root, which I started using to tell cargo-readme which crate to actually use, so I tried:

$ cargo readme -r snax -o README.md

This writes to snax/README.md instead of ./README.md like I expected! In other words, it behaves differently than:

$ cargo readme -r snax > README.md

Is this intentional?

$ cargo readme --version
cargo-readme v3.1.2