prerelease, introducing exercise file download

README.md

@@ -16,7 +16,7 @@ python pluradl.py
 ```
 
 ## Download exercise files
-To download exercise files you need the selenium external library
+To download exercise files you need the selenium external library. Then you will need an [appropriate Chrome driver](https://sites.google.com/a/chromium.org/chromedriver/downloads) and make it availaible in system/user PATH. Selenium documentation can be [found here](https://selenium-python.readthedocs.io/).
 ```bash
 pip install selenium
 python pluraexercise.py