Fix GHA status labels

Author: jballoffet

README.md

@@ -1,9 +1,8 @@
 ROS 2 for Rust
 ==============
 
-| Target | Status |
-|----------|--------|
-| **Ubuntu 20.04** | [![Build Status](https://github.com/ros2-rust/ros2_rust/actions/workflows/rust.yml/badge.svg?branch=main)](https://github.com/ros2-rust/ros2_rust/actions/workflows/rust.yml?branch=main) |
+[![GitHub Workflow Status](https://github.com/ros2-rust/ros2_rust/actions/workflows/rust-minimal.yml/badge.svg)](https://github.com/ros2-rust/ros2_rust/actions/workflows/rust-minimal.yml)
+[![GitHub Workflow Status](https://github.com/ros2-rust/ros2_rust/actions/workflows/rust-stable.yml/badge.svg)](https://github.com/ros2-rust/ros2_rust/actions/workflows/rust-stable.yml)
 
 Introduction
 ------------