additional text in /poller/services docstring

inventory_provider/routes/poller.py

@@ -711,13 +711,19 @@ def gws_direct():
 @common.require_accepts_json
 def get_services(service_type=None):
     """
-    Handler for `/poller/services/type`.
+    Handler for `/poller/services/service_type`.
 
     The response will be formatted according to the following schema:
 
     .. asjson::
        inventory_provider.routes.poller.SERVICES_LIST_SCHEMA
 
+    A few possible values for `service_type` are (currently): gws_internal,
+    geant_ip, geant_lambda, l3_vpn, md_vpn_proxy (there are more)
+
+    If the endpoint is called with no `service_type`,
+    all services are returned
+
     :return:
     """
     def _services():