document 'none' background transition

README.md

@@ -110,7 +110,7 @@ Reveal.initialize({
 	transitionSpeed: 'default', // default/fast/slow
 
 	// Transition style for full page backgrounds
-	backgroundTransition: 'default' // default/linear
+	backgroundTransition: 'default' // default/linear/none
 
 });
 ```

js/reveal.js

@@ -83,7 +83,7 @@ var Reveal = (function(){
 			transitionSpeed: 'default', // default/fast/slow
 
 			// Transition style for full page slide backgrounds
-			backgroundTransition: 'default', // default/linear
+			backgroundTransition: 'default', // default/linear/none
 
 			// Script dependencies to load
 			dependencies: []