Add warning and note about starting server for production

issue10934
review351001002

doc/topics/start_server.rst

@@ -17,6 +17,12 @@ The server will wait for client connections on the interface defined in the
 .. note:: When using multiple config files the order is importart as last
           entered files will override the items of first files
 
+.. warning::
+   This runs the of `Werkzeug`_ development server which should not be used on
+   production systems.
+
+.. _`Werkzeug`: https://werkzeug.palletsprojects.com/
+
 WSGI server
 -----------
 
@@ -45,6 +51,10 @@ long-polling request on the :ref:`bus <ref-bus>` as each client consumes
 permanently one thread.
 You can start the server with coroutine using the option ``--coroutine``.
 
+.. note::
+   This will use the pure-Python, gevent-friendly `WSGI server
+   <http://www.gevent.org/api/gevent.pywsgi.html>`_.
+
 Cron service
 ============