cli: Adjust shell complete cargo command to specify package

The README for blazecli mentions how to build the shell-complete binary,
but the command for doing so is relative to the cli/ sub-directory.
That's not the case for other commands higher up in the README.
Add the necessary package specification to make this command behave as
the others.

Signed-off-by: Daniel Müller <deso@posteo.net>

cli/README.md

@@ -47,7 +47,7 @@ completion script can be generated via the `shell-complete` utility
 program and then only needs to be sourced to make the current shell
 provide context-sensitive tab completion support. E.g.,
 ```bash
-$ cargo run --bin=shell-complete --features="clap_complete" -- bash > blazecli.bash
+$ cargo run -p blazecli --bin=shell-complete --features="clap_complete" -- bash > blazecli.bash
 $ source blazecli.bash
 ```