Update Active Job Basics [ci skip]

* Add Sneakers link to documentation list.

guides/source/active_job_basics.md

@@ -162,6 +162,7 @@ Here is a noncomprehensive list of documentation:
 
 - [Sidekiq](https://github.com/mperham/sidekiq/wiki/Active-Job)
 - [Resque](https://github.com/resque/resque/wiki/ActiveJob)
+- [Sneakers](https://github.com/jondot/sneakers/wiki/How-To:-Rails-Background-Jobs-with-ActiveJob)
 - [Sucker Punch](https://github.com/brandonhilkert/sucker_punch#active-job)
 - [Queue Classic](https://github.com/QueueClassic/queue_classic#active-job)