Script, Readme and additional Test input for A4

[annadhm]

Please Review :)

[HannahSophie08]

Hey Anna, your code successfully generates text using a Markov model. I especially like your thorough documentation and the clear structure of your code. You also did a great job considering edge cases, including the possibility of infinite loops. I like how you handled this by introducing a maximum output length.
As a possible improvement, you could give the user the option to define this limit via a command-line option, which would make this behavior more transparent and give the users more control.
Other than that I didn't find anything to improve! Great job :)