Prepare changelog for v2.8.1

Author: RiotRobot

CHANGELOG.md

@@ -1,3 +1,10 @@
+Changes in [2.8.1](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v2.8.1) (2020-06-29)
+===================================================================================================
+[Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v2.8.0...v2.8.1)
+
+ * Support accounts with cross signing but no SSSS
+   [\#4852](https://github.com/matrix-org/matrix-react-sdk/pull/4852)
+
 Changes in [2.8.0](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v2.8.0) (2020-06-23)
 ===================================================================================================
 [Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v2.8.0-rc.1...v2.8.0)