Add reconnect/list to top-level help message.

Bug:138994010
Test: acloud-dev --help
Change-Id: I1cba05a5cba8652cca0d6febc3dd16414fd1290f
diff --git a/public/acloud_main.py b/public/acloud_main.py
index abe15bd..6597113 100644
--- a/public/acloud_main.py
+++ b/public/acloud_main.py
@@ -42,6 +42,20 @@
  - Delete instances:
    $ acloud delete
 
+ - Reconnect:
+   To reconnect adb/vnc to an existing instance that's been disconnected:
+   $ acloud reconnect
+   Or to specify a specific instance:
+   $ acloud reconnect --instance-names <instance_name like ins-123-cf-x86-phone>
+
+ - List:
+   List will retrieve all the remote instances you've created in addition to any
+   local instances created as well.
+   To show device IP address, adb port and instance name:
+   $ acloud list
+   To show more detail info on the list.
+   $ acloud list -vv
+
 Try $acloud [cmd] --help for further details.
 
 """