Update README-UBUNTU.md

Author: adamdbrw

README-UBUNTU.md

@@ -30,4 +30,4 @@ Running Unity Editor through Unity Hub is also supported.
 ## Usage troubleshooting
 
 * If you see `"No ROS environment sourced. You need to source your ROS2 (..)"` message in Unity3D Editor, it means your environment was not sourced properly. This could happen if you run Unity but it redirects to Hub and ignores your console environment variables (this behavior can depend on Unity3D version). In such case, run project directly with `-projectPath` or add ros2 sourcing to your `~/.profile` file (you need to re-log for it to take effect).
-* Keep in mind that UnityHub works the whole time in the background after it's first launch. This means that environment variables are inherited and cached when process is launched for the first time. To change between Unity Assets compiled with different ros2 distributions, please kill existent UnityHub process and run it with the correct ros2 distribution sourced.
+* Keep in mind that `UnityHub` stays in the background after its first launch and Unity Editor launch without `-projectPath` will redirect to it and the Hub will start Unity Editor. Since environment variables for the process are set on launch and inherited by child processes, your sourced ros2 environment in the console launching the Editor this way won't be applied. To make sure it applies (and to change between different ros2 distributions), make sure to terminate existing UnityHub process and run it with the correct ros2 distribution sourced.