minor #7924 Syntax to create an email (grelu)

This PR was submitted for the 3.2 branch but it was merged into the 2.7 branch instead (closes #7924).

Discussion
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Syntax to create an email

With swiftmailer 6.0.1 and Symfony 3.2.8, the good syntax to create an email is :
$message = new \Swift_Message('Hello Email');

Commits
-------

f5f0f7c Syntax to create an email

Author: xabbuh

controller/soap_web_service.rst

@@ -39,9 +39,8 @@ In this case, the SOAP service will allow the client to call a method called
         public function hello($name)
         {
 
-            $message = \Swift_Message::newInstance()
+            $message = new \Swift_Message('Hello Service')
                                     ->setTo('me@example.com')
-                                    ->setSubject('Hello Service')
                                     ->setBody($name . ' says hi!');
 
             $this->mailer->send($message);

email.rst

@@ -103,8 +103,7 @@ an email is pretty straightforward::
 
     public function indexAction($name)
     {
-        $message = \Swift_Message::newInstance()
-            ->setSubject('Hello Email')
+        $message = new \Swift_Message('Hello Email')
             ->setFrom('send@example.com')
             ->setTo('recipient@example.com')
             ->setBody(

email/dev_environment.rst

@@ -100,8 +100,7 @@ Now, suppose you're sending an email to ``recipient@example.com``.
 
     public function indexAction($name)
     {
-        $message = \Swift_Message::newInstance()
-            ->setSubject('Hello Email')
+        $message = new \Swift_Message('Hello Email')
             ->setFrom('send@example.com')
             ->setTo('recipient@example.com')
             ->setBody(

email/testing.rst

@@ -14,8 +14,7 @@ Start with an easy controller action that sends an email::
 
     public function sendEmailAction($name)
     {
-        $message = \Swift_Message::newInstance()
-            ->setSubject('Hello Email')
+        $message = new \Swift_Message('Hello Email')
             ->setFrom('send@example.com')
             ->setTo('recipient@example.com')
             ->setBody('You should see me from the profiler!')