Merge note on triggering DAG via CLI into dev

The note is very helpful for people not wanting to have the web interface running all the time.

README.rst

@@ -194,8 +194,18 @@ If running :code:`egon-data` results in an error, we also have collected
 a list of `known runtime errors`_, which can consult in search of a
 solution.
 
+To run the workflow from the CLI without using :code:`egon-data serve` you can use
+
+.. code-block:: bash
+
+   egon-data airflow scheduler
+   egon-data airflow dags trigger egon-data-processing-pipeline
+
+For further details how to use the CLI see `Apache Airflow CLI Reference`_.
+
 .. _Apache Airflow: https://airflow.apache.org/docs/apache-airflow/stable/ui.html#ui-screenshots
 .. _known runtime errors: https://eGon-data.readthedocs.io/en/latest/troubleshooting.html#runtime-errors
+.. _Apache Airflow CLI Reference: https://airflow.apache.org/docs/apache-airflow/stable/cli-and-env-variables-ref.html
 
 .. warning::