The documentation for macOS only shows how to use the webots_ros2_driver
for a virtual machine, but users can also configure it to work for
Docker containers.

These are instructions for an alternative Ubuntu setup where Webots
runs natively and the ROS packages run in a Docker container. This is
most likely an uncommon setup, but the instructions are provided for
completeness.

These entries cover the macOS Finder file and the default Python
virtual environment directory name. Neither of which should be
version controlled.

Fix typos, grammatical errors, and clarify some instructions.

Fix some grammatical errors and elaborate in some areas.