Add default accumulator note to _.transform docs. [ci skip]

lodash.js

@@ -13030,15 +13030,16 @@
      * An alternative to `_.reduce`; this method transforms `object` to a new
      * `accumulator` object which is the result of running each of its own
      * enumerable string keyed properties thru `iteratee`, with each invocation
-     * potentially mutating the `accumulator` object. The iteratee is invoked
-     * with four arguments: (accumulator, value, key, object). Iteratee functions
-     * may exit iteration early by explicitly returning `false`.
+     * potentially mutating the `accumulator` object. If `accumulator` is not
+     * provided, a new object with the same `[[Prototype]]` will be used. The
+     * iteratee is invoked with four arguments: (accumulator, value, key, object).
+     * Iteratee functions may exit iteration early by explicitly returning `false`.
      *
      * @static
      * @memberOf _
      * @since 1.3.0
      * @category Object
-     * @param {Array|Object} object The object to iterate over.
+     * @param {Object} object The object to iterate over.
      * @param {Function} [iteratee=_.identity] The function invoked per iteration.
      * @param {*} [accumulator] The custom accumulator value.
      * @returns {*} Returns the accumulated value.