Docstring should say 'default' if option is default

Change-Id: I59d83e7a0a590fa537f509f7f19940640f555679

Author: rushiagr

doc/source/command-objects/compute-service.rst

@@ -57,7 +57,7 @@ Set service command
 .. _compute-service-set:
 .. describe:: --enable
 
-    Enable service
+    Enable service (default)
 
 .. describe:: --disable
 

openstackclient/compute/v2/service.py

@@ -100,7 +100,7 @@ def get_parser(self, prog_name):
             "--enable",
             dest="enabled",
             default=True,
-            help="Enable a service",
+            help="Enable a service (default)",
             action="store_true")
         enabled_group.add_argument(
             "--disable",