Added the missing "versionadded" directives

Author: javiereguiluz

reference/configuration/swiftmailer.rst

@@ -46,6 +46,9 @@ url
 
 **type**: ``string``
 
+.. versionadded:: 2.4.2
+    The ``url`` option was added in SwiftMailerBundle 2.4.2.
+
 The entire SwiftMailer configuration using a DSN-like URL format.
 
 Example: ``smtp://user:pass@host:port/?timeout=60&encryption=ssl&auth_mode=login&...``
@@ -97,20 +100,29 @@ timeout
 
 **type**: ``integer``
 
+.. versionadded:: 2.4.2
+    The ``url`` option was added in SwiftMailerBundle 2.4.2.
+
 The timeout in seconds when using ``smtp`` as the transport.
 
 source_ip
 ~~~~~~~~~
 
 **type**: ``string``
 
+.. versionadded:: 2.4.2
+    The ``url`` option was added in SwiftMailerBundle 2.4.2.
+
 The source IP address when using ``smtp`` as the transport.
 
 local_domain
 ~~~~~~~~~~~~
 
 **type**: ``string``
 
+.. versionadded:: 2.4.2
+    The ``url`` option was added in SwiftMailerBundle 2.4.2.
+
 The domain name to use in ``HELO`` command.
 
 encryption