minor #9688 Add Tip to using MailHog during developement (zairigimad, javiereguiluz)

This PR was submitted for the 4.0 branch but it was merged into the 2.8 branch instead (closes #9688).

Discussion
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Add Tip to using  MailHog during developement

Add Tip to using  MailHog during developement

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Commits
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85009fc Removed some whitespace
731986e Reworded the tip contents
acb3abd Add Tip to using  MailHog during developement

Author: javiereguiluz

email/dev_environment.rst

@@ -247,3 +247,12 @@ you to open the report with details of the sent emails.
     by the submit URL used on the previous request (e.g. ``/contact/handle``).
     The profiler's search feature allows you to load the profiler information
     for any past requests.
+
+.. tip::
+
+    In addition to the features provided by Symfony, there are applications that
+    can help you test emails during application development, like `MailCatcher`_
+    and `MailHog`_.
+
+.. _`MailCatcher`: https://github.com/sj26/mailcatcher
+.. _`MailHog`: https://github.com/mailhog/MailHog