fix example code in documentation for has_secure_password

activemodel/lib/active_model/secure_password.rb

@@ -29,7 +29,7 @@ module ActiveModel
       #   user.save                                                      # => true
       #   user.authenticate("notright")                                  # => false
       #   user.authenticate("mUc3m00RsqyRe")                             # => user
-      #   User.find_by_name("david").try(:authenticate, "notright")      # => nil
+      #   User.find_by_name("david").try(:authenticate, "notright")      # => false
       #   User.find_by_name("david").try(:authenticate, "mUc3m00RsqyRe") # => user
       def has_secure_password
         # Load bcrypt-ruby only when has_secure_password is used.