[ci skip] Tweak the Action Mailer callbacks documentation:

- Detail the order of callbacks callbacks called by Action Mailer
  when sending an email.

Author: dkani

guides/source/action_mailer_basics.md

@@ -793,13 +793,18 @@ end
 Action Mailer Callbacks
 -----------------------
 
-Action Mailer allows for you to specify a [`before_action`][],
-[`after_action`][], and [`around_action`][] to configure the message, and
-[`before_deliver`][], [`after_deliver`][] and [`around_deliver`][] to control
-the delivery.
+Action Mailer allows for you to specify `*_action` callbacks to configure the message, and `*_deliver` callbacks to control the delivery.
 
-Callbacks can be specified with a block or a symbol representing a method name
-in the mailer class, similar to other callbacks (in controllers or models).
+Here is a list with all the available Action Mailer callbacks, listed **in the order in which they will get called** when sending an email:
+
+* [`before_action`][]
+* [`around_action`][]
+* [`after_action`][]
+* [`before_deliver`][]
+* [`around_deliver`][]
+* [`after_deliver`][]
+
+Callbacks can be specified with a block or a symbol representing a method name in the mailer class, similar to other callbacks (in controllers or models).
 
 Here are some examples of when you may use one of these callbacks with mailers.