README.rst first-timer failure: "./new-package.sh foo" fails with "Couldn't find any crate matching foo"

On a minimal debian sid system i'm following the README.rst to try to create packaging for the sequoia-sqv crate.

i did apt install debcargo as the superuser, but now:

0 dkg@sid:~/src/debcargo/debcargo-conf$ ./new-package.sh sequoia-sqv
Something failed: ErrorMessage { msg: "Couldn\'t find any crate matching sequoia-sqv *\n Try `cargo update` toupdate the crates.io index" }
./new-package.sh: abort: couldn't find crate sequoia-sqv
1 dkg@sid:~/src/debcargo/debcargo-conf$ 

i tried to follow the recommendations here, but it fails because cargo is not installed:

1 dkg@sid:~/src/debcargo/debcargo-conf$ cargo update
bash: cargo: command not found
127 dkg@sid:~/src/debcargo/debcargo-conf$ 

after doing apt install cargo as the superuser, it still fails though:

0 dkg@sid:~/src/debcargo/debcargo-conf$ cargo update
error: could not find `Cargo.toml` in `/home/dkg/src/debcargo/debcargo-conf` or any parent directory
101 dkg@sid:~/src/debcargo/debcargo-conf$ 

So i think the README should be improved to make it easier for new contributors to follow along.