Fix typo

Author: Birgit Schachler

windpowerlib/modelchain.py

@@ -331,7 +331,7 @@ def run_model(self, weather, data_height):
         ----------
         weather : DataFrame or Dictionary
             Containing columns or keys with the timeseries for wind speed
-            `v_wind` in m/s ,roughness length `z0` in m, temperature
+            `v_wind` in m/s, roughness length `z0` in m, temperature
             `temp_air` in K and pressure `pressure` in Pa, as well as
             optionally wind speed `v_wind_2` in m/s and temperature
             `temp_air_2` in K at different height for interpolation.