Bump to v4.6.0.

difference.js

@@ -6,7 +6,8 @@ import rest from './rest';
 /**
  * Creates an array of unique `array` values not included in the other
  * given arrays using [`SameValueZero`](http://ecma-international.org/ecma-262/6.0/#sec-samevaluezero)
- * for equality comparisons.
+ * for equality comparisons. The order of result values is determined by the
+ * order they occur in the first array.
  *
  * @static
  * @memberOf _