Fine tune some of the helps commands

try and add some consistency with the show and delete commands.

replace 'show x' with 'display x'
change 'delete a y' with just 'delete y'

Change-Id: I47dfa8ee23ac5c41b355796415eb515155832f65

openstackclient/compute/v2/aggregate.py

@@ -290,7 +290,7 @@ class SetAggregate(show.ShowOne):
 
 
 class ShowAggregate(show.ShowOne):
-    """Show a specific aggregate"""
+    """Display aggregate details"""
 
     log = logging.getLogger(__name__ + '.ShowAggregate')
 
@@ -299,7 +299,7 @@ class ShowAggregate(show.ShowOne):
         parser.add_argument(
             'aggregate',
             metavar='<aggregate>',
-            help='Aggregate to show (name or ID)',
+            help='Aggregate to display (name or ID)',
         )
         return parser