Updated the help text for the performance management command.

Change-Id: I26727fd9eede95a86d87d4b33a9f06a1bbc1da34
diff --git a/cli/device.py b/cli/device.py
index 37513df..3945008 100644
--- a/cli/device.py
+++ b/cli/device.py
@@ -89,9 +89,23 @@
     def help_perf_config(self):
         self.poutput(
 '''
-perfo_config [show | set | commit | reset] [-f <default frequency>] [-e <metric/group
-            name>] [-d <metric/group name>] [-o <metric/group name> <override
-            frequency>]
+perf_config [show | set | commit | reset] [-f <default frequency>] [{-e <metric/group
+            name>}] [{-d <metric/group name>}] [{-o <metric/group name> <override
+            frequency>}]
+
+show: displays the performance configuration of th device
+set: changes the parameters specified with -e, -d, and -o
+reset: reverts any changes made since the last commit
+commit: commits any changes made which applies them to the device.
+
+-e: enable collection of the specified metric, more than one -e may be
+            specified.
+-d: disable collectio of the specified metric, more than on -d may be
+            specified.
+-o override the collection frequency of the specified metric, more than one -o
+            may be specified. Note that -o isn't valid unless
+            frequency_overried is set to True for the device.
+
 Changes made by set are held locally until a commit or reset command is issued.
 A commit command will write the configuration to the device and it takes effect
 immediately. The reset command will undo any changes sinc the start of the