update the changelog

Author: zloirock

CHANGELOG.md

@@ -1,6 +1,6 @@
 ## Changelog
 ##### Unreleased
-- Nothing
+- Fixed microtask implementation on iOS Pebble, [#967](https://github.com/zloirock/core-js/issues/967)
 
 ##### 3.16.0 - 2021.07.30
 - [`Array` find from last proposal](https://github.com/tc39/proposal-array-find-from-last) moved to the stage 3, [July 2021 TC39 meeting](https://github.com/tc39/proposal-array-find-from-last/pull/47)