fix path to c++ generator example
diff --git a/README.md b/README.md
index 1b1611d..04cabd0 100644
--- a/README.md
+++ b/README.md
@@ -120,7 +120,7 @@
 $ cargo expand --manifest-path demo-rs/Cargo.toml
 
    # run C++ code generator and print to stdout
-$ cargo run --manifest-path cmd/Cargo.toml -- demo-rs/src/main.rs
+$ cargo run --manifest-path gen/cmd/Cargo.toml -- demo-rs/src/main.rs
 ```
 
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