Add changes to whatsnew

Author: birgits

doc/whatsnew/v0-2-0.txt

@@ -23,6 +23,7 @@ API changes
 * Combined options 'constant_efficiency' and 'power_efficiency_curve' of `wake_losses_model` parameter in :py:func:`~.turbine_cluster_modelchain.TurbineClusterModelChain` to 'wind_farm_efficiency'. Therefore, default value of `wake_losses_model` in :py:func:`~.wind_farm.WindFarm.assign_power_curve` and :py:func:`~.wind_turbine_cluster.WindTurbineCluster.assign_power_curve` changed to 'wind_farm_efficiency'.
 * Removed `overwrite` parameter from :py:func:`~.wind_turbine.get_turbine_data_from_oedb`
 * Removed `data_source` and `fetch_curve` parameters from :py:func:`~.wind_turbine.WindTurbine` and :py:func:`~.wind_turbine.WindTurbine.fetch_turbine_data`. Now the source and if a curve is fetched or not is specified by the parameters `power_curve`, `power_coefficient_curve` and `nominal_power`. See :py:func:`~.wind_turbine.WindTurbine.fetch_turbine_data` for a description.
+* get_installed_power() methods in :class:`~windpowerlib.wind_farm.WindFarm` and  :class:`~windpowerlib.wind_turbine_cluster.WindTurbineCluster` were removed. Installed power is instead now directly calculated inside the nominal_power getter.
 
 Other changes
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@@ -36,4 +37,5 @@ Deprecations
 Contributors
 ############
 * Sabine Haas
+* Birgit Schachler