Modify help msg and docs in identity

Migrate 'change', 'update' to 'modify',
migrate 'user to delete' to 'user(s) to delete',
migrate '(name or ID)' to '(type, name or ID)'.

Change-Id: Ie425e178bb5ddf773e6e793fcd91c78e9c4a5053

Author: sunyajing

doc/source/command-objects/service.rst

@@ -117,7 +117,7 @@ Set service properties
 .. _service_set-service:
 .. describe:: <service>
 
-    Service to update (type, name or ID)
+    Service to modify (type, name or ID)
 
 service show
 ------------

doc/source/command-objects/user.rst

@@ -95,7 +95,7 @@ Delete user(s)
 .. _user_delete-user:
 .. describe:: <user>
 
-    User to delete (name or ID)
+    User(s) to delete (name or ID)
 
 user list
 ---------

openstackclient/identity/v2_0/service.py

@@ -94,7 +94,7 @@ def get_parser(self, prog_name):
         parser.add_argument(
             'service',
             metavar='<service>',
-            help=_('Service to delete (name or ID)'),
+            help=_('Service to delete (type, name or ID)'),
         )
         return parser
 

openstackclient/identity/v2_0/user.py

@@ -240,7 +240,7 @@ def get_parser(self, prog_name):
         parser.add_argument(
             'user',
             metavar='<user>',
-            help=_('User to change (name or ID)'),
+            help=_('User to modify (name or ID)'),
         )
         parser.add_argument(
             '--name',

openstackclient/identity/v3/service.py

@@ -130,7 +130,7 @@ def get_parser(self, prog_name):
         parser.add_argument(
             'service',
             metavar='<service>',
-            help=_('Service to update (type, name or ID)'),
+            help=_('Service to modify (type, name or ID)'),
         )
         parser.add_argument(
             '--type',

openstackclient/identity/v3/user.py

@@ -273,7 +273,7 @@ def get_parser(self, prog_name):
         parser.add_argument(
             'user',
             metavar='<user>',
-            help=_('User to change (name or ID)'),
+            help=_('User to modify (name or ID)'),
         )
         parser.add_argument(
             '--name',