README.md aktualisiert

README.md

@@ -19,6 +19,12 @@ Assuming `python3` is already installed, you can use the following command to in
 pip3 install csv numpy sounddevice
 ```
 
+If you need the GUI, additionally install PySimpleGui
+
+```bash
+pip3 install PySimpleGui
+```
+
 After that, simply run `python3 offitracker.py` and enjoy. The command can also take a path to a file as a parameter if you wish to use your shells autocompletion.
 
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