Prepare changelog for v2.3.1

Author: RiotRobot

CHANGELOG.md

@@ -1,3 +1,14 @@
+Changes in [2.3.1](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v2.3.1) (2020-04-01)
+===================================================================================================
+[Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v2.3.0...v2.3.1)
+
+ * Fix jitsi popout URL
+   [\#4327](https://github.com/matrix-org/matrix-react-sdk/pull/4327)
+ * Remove underscore from Jitsi conference names
+   [\#4324](https://github.com/matrix-org/matrix-react-sdk/pull/4324)
+ * Fix popout support for jitsi widgets
+   [\#4322](https://github.com/matrix-org/matrix-react-sdk/pull/4322)
+
 Changes in [2.3.0](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v2.3.0) (2020-03-30)
 ===================================================================================================
 [Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v2.3.0-rc.1...v2.3.0)