Update Launch Instructions in README

[Eric-YLL]

What happened?

file 'launch_sim.launch.py' was not found in the share directory of package 'robolaunch_cloudy_simulator' which is at '/home/yanlulu/cloudy_ws/install/robolaunch_cloudy_simulator/share/robolaunch_cloudy_simulator'

What did you expect to happen?

I cannot find the file "launch_sim.launch.py" in folder "robolaunch_cloudy_sim/launch "

How can we reproduce it (as minimally and precisely as possible)?

Launch the simulation
ros2 launch robolaunch_cloudy_simulator launch_sim.launch.py

[tunahanertekin]

Looks like the README is out of date. Have you tried launching gazebo.launch.py?

[Eric-YLL]

Looks like the README is out of date. Have you tried launching gazebo.launch.py?

[gzserver-2] Error [Converter.cc:113] Unable to convert from SDF version 1.9 to 1.7

and nothing is displayed in Gazebo window

[Eric-YLL]

Looks like the README is out of date. Have you tried launching gazebo.launch.py?

I have replaced the world file, and it is functioning properly. Thank you.

[tunahanertekin]

Glad you handled it. Converted the issue to docs issue.