Can't find any of the "real application packages" referenced in the top-level README.md file

## Issue template

- Version or commit hash: galactic branch

#### Steps to reproduce the issue
In [README.md](https://github.com/micro-ROS/micro-ROS-demos/tree/galactic#real-application-packages), there is reference to the following packages:
- [rad0_actuator](https://github.com/micro-ROS/micro-ROS-demos/tree/galactic#rad0_actuator)
- [rad0_altitude_sensor](https://github.com/micro-ROS/micro-ROS-demos/tree/galactic#rad0_altitude_sensor)
- [rad0_control](https://github.com/micro-ROS/micro-ROS-demos/tree/galactic#rad0_control)
- [rad0_display](https://github.com/micro-ROS/micro-ROS-demos/tree/galactic#rad0_display)

However, I can't seem to find that code anywhere. Would you mind adding github links to the corresponding source files for those sections?

The only package I see that seems related is the [RAD0_control](https://github.com/micro-ROS/micro-ROS-demos/tree/galactic/rclcpp/RAD0_control) package, but that doesn't have any of the functionality referenced above.

Review the Real Application Packages section in README.md and compare its rad0_actuator, rad0_altitude_sensor, rad0_control, and rad0_display references with the repository contents. Check the existing rclcpp/RAD0_control package, then update the section with links to the corresponding source locations or correct references so each listed package is discoverable.

Written by the indexing model from the issue text.