Fix missing backtick in mailer guide

Also remove extraneous line break from paragraph in configuring guide
related to mailer config.

[ci skip]

guides/source/action_mailer_basics.md

@@ -818,7 +818,7 @@ files (environment.rb, production.rb, etc...)
 |`perform_deliveries`|Determines whether deliveries are actually carried out when the `deliver` method is invoked on the Mail message. By default they are, but this can be turned off to help functional testing. If this value is `false`, `deliveries` array will not be populated even if `delivery_method` is `:test`.|
 |`deliveries`|Keeps an array of all the emails sent out through the Action Mailer with delivery_method :test. Most useful for unit and functional testing.|
 |`delivery_job`|The job class used with `deliver_later`. Defaults to `ActionMailer::MailDeliveryJob`.|
-|`deliver_later_queue_name`|The name of the queue used with the default `delivery_job`. Defaults to `:mailers|
+|`deliver_later_queue_name`|The name of the queue used with the default `delivery_job`. Defaults to `:mailers`|
 |`default_options`|Allows you to set default values for the `mail` method options (`:from`, `:reply_to`, etc.).|
 
 For a complete writeup of possible configurations see the

guides/source/configuring.md

@@ -2120,8 +2120,7 @@ Specifies whether the mailer templates should perform fragment caching or not. I
 
 Specifies the Active Job queue to use for the default delivery job (see `config.action_mailer.delivery_job`). When this option is set to `nil`, delivery jobs are sent to the default Active Job queue (see `config.active_job.default_queue_name`).
 
-Mailer classes can override this to use a different queue. Note that this only applies when using the default delivery job. If your mailer is using a custom
-job, its queue will be used.
+Mailer classes can override this to use a different queue. Note that this only applies when using the default delivery job. If your mailer is using a custom job, its queue will be used.
 
 Ensure that your Active Job adapter is also configured to process the specified queue, otherwise delivery jobs may be silently ignored.