Fix "endpoint list" help message

OSC support to filter OpenStack endpoints by service type, name and ID,
but help message and document don't contain "type" for "--service"
option of "endpoint list" command.

Change-Id: I5c8bc28e037b4c6f96ec83525a319353f01f256a
Closes-Bug: #1666841

doc/source/command-objects/endpoint.rst

@@ -103,14 +103,14 @@ List endpoints
 .. code:: bash
 
     openstack endpoint list
-        [--service <service]
+        [--service <service>]
         [--interface <interface>]
         [--region <region-id>]
         [--long]
 
 .. option:: --service <service>
 
-    Filter by service (name or ID)
+    Filter by service (type, name or ID)
 
     *Identity version 3 only*
 

openstackclient/identity/v3/endpoint.py

@@ -139,7 +139,7 @@ class ListEndpoint(command.Lister):
         parser.add_argument(
             '--service',
             metavar='<service>',
-            help=_('Filter by service (name or ID)'),
+            help=_('Filter by service (type, name or ID)'),
         )
         parser.add_argument(
             '--interface',