fix bad changelog example

actionmailer/CHANGELOG.md

@@ -6,7 +6,7 @@
   you can now override settings per mail instance for e.g.
 
       def my_mailer(user,company)
-        mail to: customer.email, subject: "Welcome!",
+        mail to: user.email, subject: "Welcome!",
              delivery_method_options: {user_name: company.smtp_user,
                                        password: company.smtp_password}
       end