feature #3940 Updated docs for Monolog "swift" handler in cookbook. (phansys)

This PR was merged into the 2.3 branch.

Discussion
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Updated docs for Monolog "swift" handler in cookbook.

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | no
| Applies to    | 2.1+
| Fixed tickets |

.. versionadded:: 2.1
    Support for multiple recipients is a new Monolog feature that's available in
    Symfony 2.1. Prior, only a single email address was accepted as `monolog.handlers.swift.to_email` configuration.

Commits
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86e236c Updated docs for Monolog "swift" handler in cookbook.

Author: weaverryan

Diff for: cookbook/logging/monolog_email.rst

@@ -28,6 +28,8 @@ it is broken down.
                     type:       swift_mailer
                     from_email: [email protected]
                     to_email:   [email protected]
+                    # or list of recipients
+                    # to_email:   [[email protected], [email protected], ...]
                     subject:    An Error Occurred!
                     level:      debug