Run ROS Melodic with Gazebo 9

[syedjawadakhtar]

Thank you for the docker files, as I've been new to dockers and ROS, and this will help a lot to a lot of people who are always stuck in setting up environments.

I'm trying to setup the docker for ROS melodic with Gazebo 9 to test this repository (https://github.com/Livox-SDK/livox_laser_simulation). I already have ROS2 Humble installed on my WSL2.
I've a few questions:

1. Looking at the wiki for How to build a Docker file, I don't see which directory to go to to execute the docker command? As docker_files/ros/ros-melodic has many other project related directories.
2. I executed the commands docker build -t ros_gazebo_img:melodic_11 . in the ros/ros-melodic/moveit_ros which downloaded tile the RUN sudo rosdep init line which led to an error

Dockerfile:102
--------------------
 100 |
 101 |     RUN sudo rosdep init
 102 | >>> RUN rosdep update
 103 |
 104 |     # Init ROS workspace
--------------------
ERROR: failed to solve: process "/bin/sh -c rosdep update" did not complete successfully: exit code: 1

Let me know if I should provide more information.