[Optimize] Update help text for hint argument

Update scheduler_hint's help text to describe
how to specify multiple hints and array value.

Change-Id: If975e06b6e9914848498fa2c3ab27c2f41d7860b

cinderclient/v2/shell.py

@@ -294,7 +294,9 @@ class CheckSizeArgForCreate(argparse.Action):
            dest='scheduler_hints',
            action='append',
            default=[],
-           help='Scheduler hint, like in nova.')
+           help='Scheduler hint, similar to nova. Repeat option to set '
+                'multiple hints. Values with the same key will be stored '
+                'as a list.')
 @utils.arg('--allow-multiattach',
            dest='multiattach',
            action="store_true",

cinderclient/v3/shell.py

@@ -564,7 +564,9 @@ def do_reset_state(cs, args):
            dest='scheduler_hints',
            action='append',
            default=[],
-           help='Scheduler hint, like in nova.')
+           help='Scheduler hint, similar to nova. Repeat option to set '
+                'multiple hints. Values with the same key will be stored '
+                'as a list.')
 @utils.arg('--allow-multiattach',
            dest='multiattach',
            action="store_true",