Reformat the Email README

Author: purinkle

email/README.md

@@ -1,10 +1,11 @@
 # Email
 
-- Use [SendGrid] or [Amazon SES] to deliver email in staging and production
+- Use [SendGrid][] or [Amazon SES][] to deliver email in staging and production
   environments.
-- Use a tool like [ActionMailer Preview] to look at each created or updated
-  mailer view before merging. 
 
+- Use a tool like [ActionMailer Preview][] to look at each created or updated
+  mailer view before merging.
+
+[actionmailer preview]: https://guides.rubyonrails.org/action_mailer_basics.html#previewing-and-testing-mailers
 [amazon ses]: https://thoughtbot.com/blog/deliver-email-with-amazon-ses-in-a-rails-app
 [sendgrid]: https://devcenter.heroku.com/articles/sendgrid
-[actionmailer preview]: https://guides.rubyonrails.org/action_mailer_basics.html#previewing-and-testing-mailers