[Bug]: Update documentation for acting_testing.md

[vinzenzm]

Current Behavior

In acting_testing.md there are descriptions on how to modify the launch scripts in order to start an empty world and test only acting.
Since the markdown file was written the launch routine and scripts got changed.

Expected Behavior

The description in markdown can be followed step by step in order to achieve expected results.

How to reproduce the issue

• [] understand how the modification of files used to work
• [] update the documentation
• [] verify that new documentation works