docs: point README CI badges at the actual workflow files

The previous badge referenced a legacy `ros2.yaml` workflow that no
longer exists. Replace with badges for the current workflows:
ros-humble, ros-jazzy, ros-rolling, and pre-commit.

Author: facontidavide

README.md

@@ -1,4 +1,6 @@
-[![ros2](https://github.com/PlotJuggler/plotjuggler-ros-plugins/actions/workflows/ros2.yaml/badge.svg)](https://github.com/PlotJuggler/plotjuggler-ros-plugins/actions/workflows/ros2.yaml)
+[![ROS2 Humble](https://github.com/PlotJuggler/plotjuggler-ros-plugins/actions/workflows/ros-humble.yaml/badge.svg)](https://github.com/PlotJuggler/plotjuggler-ros-plugins/actions/workflows/ros-humble.yaml)
+[![ROS2 Jazzy](https://github.com/PlotJuggler/plotjuggler-ros-plugins/actions/workflows/ros-jazzy.yaml/badge.svg)](https://github.com/PlotJuggler/plotjuggler-ros-plugins/actions/workflows/ros-jazzy.yaml)
+[![ROS2 Rolling](https://github.com/PlotJuggler/plotjuggler-ros-plugins/actions/workflows/ros-rolling.yaml/badge.svg)](https://github.com/PlotJuggler/plotjuggler-ros-plugins/actions/workflows/ros-rolling.yaml)
 
 # ROS plugins for PlotJuggler