added message if script is executed independently

functions/calculation_rules.py

@@ -4,4 +4,5 @@ File consists of several functions for the calculation rules of FAIR Quality KPI
 
 
 if __name__ == "__main__":
+    print("This script contains functions for calculating the FAIR Quality KPIs. It is not to be executed independently.")
     pass
\ No newline at end of file