Update README.md

Author: CARME Antoine

README.md

@@ -92,6 +92,7 @@ The following features are available :
       are estimated using scikit-learn linear regression models.
       * Standard performance measures are used (L1, RMSE, MAPE, etc)
    4. PyAF analyzes the **time variable** and infers the frequency from the data.
+      * Natural time frequencies are supported : Minute, Hour,  Day, Week, Month.
       * Strange frequencies like every 3.2 days or every 17 minutes are supported if data are recorded accordingly (every other Monday => two weeks frequency).
       * The frequency is computed as the mean duration between consecutive observations by default (as a [pandas DateOffset](https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.tseries.offsets.DateOffset.html)).
       * The frequency is used to generate values for future dates automatically.