[docs] Add a reference to native_toolchain_rs (#2720)

Author: dcharkes

README.md

@@ -50,6 +50,7 @@ Packages not on this repo but also related to FFI and native assets. ❤️
 | [native_toolchain_cmake](https://github.com/rainyl/native_toolchain_cmake) | A library to invoke CMake for Dart Native Assets. | [![pub package](https://img.shields.io/pub/v/native_toolchain_cmake.svg)](https://pub.dev/packages/native_toolchain_cmake) |
 | [native_toolchain_go](https://github.com/csnewman/flutter-go-bridge/tree/master/native_toolchain_go) | A library to invoke the native Go compiler installed on the host machine. | [![pub package](https://img.shields.io/pub/v/native_toolchain_go.svg)](https://pub.dev/packages/native_toolchain_go) |
 | [native_toolchain_rust](https://github.com/irondash/native_toolchain_rust) | A library to invoke the native Rust compiler installed on the host machine. | [![pub package](https://img.shields.io/pub/v/native_toolchain_rust.svg)](https://pub.dev/packages/native_toolchain_rust) |
+| [native_toolchain_rs](https://github.com/GregoryConrad/native_toolchain_rs) | A library to build and bundle Rust code for Dart Native Assets. | [![pub package](https://img.shields.io/pub/v/native_toolchain_rs.svg)](https://pub.dev/packages/native_toolchain_rs) |
 
 ## Publishing automation