Add readme info about simulators

[XavierVal]

Add readme info about simulators usage and configuration

[XavierVal]

From @fgalan:
Use the -t parameter to specify accuracy level, either -t s o -t ms. This way, the script will be also useful in scenarios where the spected delay is in the order of seconds.
It should be analyzed if the same functionality could be achieved using just Date class in JavaScript, without needing the moment library. @crbrox could have some suggestion regarding this, please contact him.