Docstring correction

Author: SabineHaas

example/turbine_cluster_modelchain_example.py

@@ -130,8 +130,8 @@ class that provides all necessary steps to calculate the power output of a
         Contains weather data time series.
     example_farm : WindFarm
         WindFarm object.
-    example_farm_2 : WindFarm
-        WindFarm object constant wind farm efficiency and coordinates.
+    example_cluster : WindTurbineCluster
+        WindTurbineCluster object.
 
     """