Add v3.22.0-beta.2 to CHANGELOG

(cherry picked from commit a409f1d)

Author: kategengler

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Ember Changelog
 
+### v3.22.0-beta.2 (August 31, 2020)
+
+- [#19106](https://github.com/emberjs/ember.js/pull/19106) [BUGFIX] Ensure `destroy` methods on `CoreObject` are invoked.
+- [#19111](https://github.com/emberjs/ember.js/pull/19111) [BUGFIX] Fixes `ArrayProxy` length reactivity.
+
 ### v3.22.0-beta.1 (August 24, 2020)
 
 - [#19062](https://github.com/emberjs/ember.js/pull/19062) / [#19068](https://github.com/emberjs/ember.js/pull/19068) [FEATURE] Add @ember/destroyable feature from the [Destroyables RFC](https://github.com/emberjs/rfcs/blob/master/text/0580-destroyables.md).