Minor changes in docstrings

Author: SabineHaas

example/further_example.py

@@ -1,7 +1,7 @@
 """
 The ``further_example`` module shows a further usage of the windpowerlib.
 
-In this example uses functions from the ``basic_example`` module where the
+This example uses functions from the ``basic_example`` module where the
 basic usage of the windpowerlib is shown.
 
 

windpowerlib/wind_turbine_cluster.py

@@ -1,9 +1,9 @@
 """
 The ``wind_turbine_cluster`` module contains the class WindTurbineCluster that
-implements a wind turbine cluster in the windpowerlib and functions needed for
-the modelling of a wind turbine cluster.
-A wind turbine cluster comprises wind farms belonging to the same weather
-data grid point.
+implements a wind turbine cluster in the windpowerlib and provides functions
+needed for modelling a wind turbine cluster.
+A wind turbine cluster comprises wind farms and wind turbines belonging to the
+same weather data point.
 
 """