Add note about supported ROS versions (#6)

Author: fmauch

README.md

@@ -3,8 +3,11 @@ This package contains tutorials around the ROS 2 packages for Universal Robots.
 
 ## Getting started
 To use the tutorials from this repository, please make sure to [install ROS
-2](https://docs.ros.org/en/rolling/Installation.html) on your system. With that, please create a
-workspace, clone this repo into the workspace, install the dependencies and build the workspace.
+2](https://docs.ros.org/en/rolling/Installation.html) on your system. Currently, only ROS Jazzy and
+Rolling are supported.
+
+With that, please create a workspace, clone this repo into the workspace, install the dependencies
+and build the workspace.
 
 1. Create a colcon workspace:
    ```