Apple has just officially released OS X 10.11.5 El Capitan to the public with a number of bug fixes tagging along for the ride. Unfortunately, Apple doesn't take a deep dive into what's new, simply noting bug fixes, performance and security improvements.
Here's the the official rundown of what's new in OS X 10.11.5:
The OS El Capitan 10.11.5 update improves the stability, compatibility and security of you Mac, and is recommended for all El Capitan users.
This is the fourth public update to OS X El Capitan since it was released in September 2015. If you'd like to update your Mac, you should be able to start downloading the update through the Updates section of the Mac App Store now.