added ad updated some YARD to observable

Author: mighe

lib/concurrent/atomic/copy_on_notify_observer_set.rb

@@ -12,9 +12,10 @@ def initialize
     end
 
     # Adds an observer to this set
+    # If a block is passed, the observer will be created by this method and no other params should be passed
     # @param [Object] observer the observer to add
     # @param [Symbol] func the function to call on the observer during notification. Default is :update
-    # @return [Symbol] the added function
+    # @return [Object] the added observer
     def add_observer(observer=nil, func=:update, &block)
       if observer.nil? && block.nil?
         raise ArgumentError, 'should pass observer as a first argument or block'

lib/concurrent/atomic/copy_on_write_observer_set.rb

@@ -11,9 +11,10 @@ def initialize
     end
 
     # Adds an observer to this set
+    # If a block is passed, the observer will be created by this method and no other params should be passed
     # @param [Object] observer the observer to add
     # @param [Symbol] func the function to call on the observer during notification. Default is :update
-    # @return [Symbol] the added function
+    # @return [Object] the added observer
     def add_observer(observer=nil, func=:update, &block)
       if observer.nil? && block.nil?
         raise ArgumentError, 'should pass observer as a first argument or block'

lib/concurrent/observable.rb

@@ -5,19 +5,23 @@ module Concurrent
 
   module Observable
 
+    # @return [Object] the added observer
     def add_observer(*args, &block)
       observers.add_observer(*args, &block)
     end
 
+    # @return [Object] the deleted observer
     def delete_observer(*args)
       observers.delete_observer(*args)
     end
 
+    # @return [Observable] self
     def delete_observers
       observers.delete_observers
       self
     end
 
+    # @return [Integer] the observers count
     def count_observers
       observers.count_observers
     end