minor #5684 Fix delivery_whitelist regex (gonzalovilaseca)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #5684).

Discussion
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Fix delivery_whitelist regex

Commits
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56d1768 Fix delivery_whitelist regex

Author: xabbuh

cookbook/email/dev_environment.rst

@@ -140,11 +140,11 @@ by adding the ``delivery_whitelist`` option:
             delivery_whitelist:
                # all email addresses matching this regex will *not* be
                # redirected to [email protected]
-               - "/@specialdomain.com$/"
+               - "/@specialdomain\.com$/"
 
                # all emails sent to [email protected] won't
                # be redirected to [email protected] too
-               - "/^[email protected]$/"
+               - "/^admin@mydomain\.com$/"
 
     .. code-block:: xml
 
@@ -156,10 +156,10 @@ by adding the ``delivery_whitelist`` option:
 
         <swiftmailer:config delivery-address="[email protected]">
             <!-- all email addresses matching this regex will *not* be redirected to [email protected] -->
-            <swiftmailer:delivery-whitelist-pattern>/@specialdomain.com$/</swiftmailer:delivery-whitelist-pattern>
+            <swiftmailer:delivery-whitelist-pattern>/@specialdomain\.com$/</swiftmailer:delivery-whitelist-pattern>
 
             <!-- all emails sent to [email protected] won't be redirected to [email protected] too -->
-            <swiftmailer:delivery-whitelist-pattern>/^[email protected]$/</swiftmailer:delivery-whitelist-pattern>
+            <swiftmailer:delivery-whitelist-pattern>/^admin@mydomain\.com$/</swiftmailer:delivery-whitelist-pattern>
         </swiftmailer:config>
 
     .. code-block:: php
@@ -170,11 +170,11 @@ by adding the ``delivery_whitelist`` option:
             'delivery_whitelist' => array(
                 // all email addresses matching this regex will *not* be
                 // redirected to [email protected]
-                '/@specialdomain.com$/',
+                '/@specialdomain\.com$/',
 
                 // all emails sent to [email protected] won't be
                 // redirected to [email protected] too
-                '/^[email protected]$/',
+                '/^admin@mydomain\.com$/',
             ),
         ));