Doc: Fix link in network flavors

Rendered incorrectly.

Change-Id: I206dd8affa45864e406796147665c94684e9bf4d

Author: ankur-odl

doc/source/command-objects/network-flavor.rst

@@ -26,7 +26,7 @@ Create network flavor
 .. option:: --service-type <service-type>
 
     Service type to which the flavor applies to: e.g. VPN.
-    (See openstack :ref:`network_service_provider_list`) (required)
+    (See openstack :ref:`\<service providers\> <network_service_provider_list>`) (required)
 
 .. option:: --description <description>