better documentation for Class descendants

lib/xcake/core_ext/class.rb

@@ -1,9 +1,14 @@
 module Xcake
   module CoreExtensions
-    # Returns all descendants of a class
+    # @example  Including in a class
+    #           Class.send(:include, Xcake::CoreExtensions::ClassDescendants) # done with send because of old ruby versions
     #
-    def descendants
-      ObjectSpace.each_object(singleton_class).select { |klass| klass < self }
+    module ClassDescendants
+      # Returns all descendants of a class
+      #
+      def descendants
+        ObjectSpace.each_object(singleton_class).select { |klass| klass < self }
+      end
     end
   end
 end

lib/xcake/generator.rb

@@ -3,7 +3,7 @@ class Generator
     include Dependency
     include Plugin
     include Visitor
-    Class.send(:include, CoreExtensions) # done with send because of old ruby versions
+    Class.send(:include, CoreExtensions::ClassDescendants) # done with send because of old ruby versions
 
     attr_accessor :context
 

spec/core_ext/class_spec.rb

@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 class Parent
-  Class.send(:include, Xcake::CoreExtensions) # done with send because of old ruby versions
+  Class.send(:include, Xcake::CoreExtensions::ClassDescendants) # done with send because of old ruby versions
 end
 
 class Child < Parent