Google has updated the quality raters guidelines PDF on March 28, 2016. The full version of the quality raters guidelines was first introduced in November 2015 and now keeps it live and updated for all to see.
I am not going to go through all the changes, there are tons, but Jennifer Slegg killed her weekend doing all that work. It is massive, so you can read here detailed summary of the changes.
In short, she explained that there is more supplementary content, emphasis on the E-A-T (Expertise, Authoritativeness, Trustworthiness) section. In any event, it is worth a read when you have time and Jennifer Slegg posted an excellent summary.
Let's not forget, Paul Haahr of Google says this is actionable stuff in the raters guidelines.
Here is the full updated version.
Forum discussion at Google+.