minor #4117 Added a note about the automatic handling of the memory spool in the CLI (stof)

This PR was merged into the 2.3 branch.

Discussion
----------

Added a note about the automatic handling of the memory spool in the CLI

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3+
| Fixed tickets | n/a

since symfony/swiftmailer-bundle#64 flushing the memory spool manually is not necessary anymore when using Symfony 2.3+. I added a versionadded note here, but we might decide to remove the obsolete paragraph instead, making the cookbook only about generating urls (which would require renaming the page then)

Commits
-------

c99c70d Added a note about the automatic handling of the memory spool in the CLI

Author: weaverryan

cookbook/console/sending_emails.rst

@@ -88,6 +88,10 @@ from the ``router`` service and override its settings::
 Using Memory Spooling
 ---------------------
 
+.. versionadded: 2.3
+    When using Symfony 2.3+ and SwiftmailerBundle 2.3.5+, the memory spool is now
+    handled automatically in the CLI and the code below is not necessary anymore.
+
 Sending emails in a console command works the same way as described in the
 :doc:`/cookbook/email/email` cookbook except if memory spooling is used.