Apply descriptions to all top level commands

vultron/cmds/application.py

@@ -1,6 +1,8 @@
 import vultron.cmd
 
 class Application(vultron.cmd.Command):
+  """Query for information on Vultr applications."""
+
   def init(self):
     self.needs_api_key = False
 

vultron/cmds/backup.py

@@ -1,6 +1,8 @@
 import vultron.cmd
 
 class Backup(vultron.cmd.Command):
+  """Query for information on instance backups."""
+
   def vultron_list(self):
     """Display all stored snapshots."""
 

vultron/cmds/help.py

@@ -3,6 +3,8 @@ import vultron.cmd
 import vultron.display
 
 class Help(vultron.cmd.Command):
+  """This help message."""
+
   def init(self):
     self.needs_api_key = False