It doesn't call it rule 0 anymore but the essence is contained in many places in the DMG.
For example on pages 5-6 include references to changing published material (and rules).
Page 14+ specifically addresses changeing the rules.
These are the ones I can find quickly I know there are other inferences.
Basically they incorporated rule 0 into various parts of the book to make it more "natural" transition and part of the game play.