Merge pull request #140 from obrok/patch-2

Improve comment wording

Author: jdantonio

lib/concurrent/actor/behaviour/supervised.rb

@@ -2,7 +2,7 @@ module Concurrent
   module Actor
     module Behaviour
 
-      # Sets nad holds the supervisor of the actor if any. There is only one or none supervisor
+      # Sets and holds the supervisor of the actor if any. There is at most one supervisor
       # for each actor. Each supervisor is automatically linked.
       class Supervised < Abstract
         attr_reader :supervisor