Fix typo in activemodel changelog

activemodel/CHANGELOG.md

 *   Validate multiple contexts on `valid?` and `invalid?` at once.
 
     Example:
-    
+
         class Person
           include ActiveModel::Validations
-    
+
           attr_reader :name, :title
           validates_presence_of :name, on: :create
           validates_presence_of :title, on: :update
         end
-    
+
         person = Person.new
-        person.valid?([:create, :update])    # => true
+        person.valid?([:create, :update])    # => false
         person.errors.messages               # => {:name=>["can't be blank"], :title=>["can't be blank"]}
 
     *Dmitry Polushkin*