Add EarlGrey 2.2.1 release notes to Changelog file.

PiperOrigin-RevId: 346667284

Author: chan-park

CHANGELOG.md

@@ -1,3 +1,29 @@
+## [2.2.1](https://github.com/google/EarlGrey/tree/2.2.0) (12/9/2020)
+```
+Baseline: [91dc49f]
++ [91dc49f]: Move test-side screenshot to XCUIScreen.
+```
+
+### Enhancements
+* Improved synchronization by performing most of the GREYActions on the main thread right after matching.
+* Improved synchronization by tracking all NSTimers added in the main thread.
+* Added EarlGrey API so that users can choose the root matcher for subsequent interactions.
+* Verbose logging can be added through NSUserDefaults.
+* iOS 14 support has been added for location alert strings.
+* Dedupe superview/subview pair if accessibility attributes are the same as this is a valid case.
+
+### Bug fixes
+* Fix scrolling synchronization issue where tapping was failing at the end of scroll action.
+* Fix crash when GREYConfiguration methods were called before relaunching the application.
+* Fix crash when error screenshot was taken on the test side.
+
+### Compatibility
+* EarlGrey has been tested for working till Xcode version 12.2 and Swift 5.
+
+### Known Issues
+* There are animation issues with Context Menu’s and multi-window animations.
+* ASAN, UBSAN and TSAN do not work with EarlGrey at the moment.
+
 ## [2.2.0](https://github.com/google/EarlGrey/tree/2.2.0) (10/9/2020)
 ```
 Baseline: [ddf2911]