Prepare changelog for v3.16.0

Author: RiotRobot

CHANGELOG.md

@@ -1,3 +1,12 @@
+Changes in [3.16.0](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v3.16.0) (2021-03-15)
+=====================================================================================================
+[Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v3.16.0-rc.2...v3.16.0)
+
+ * [Release] Change read receipt drift to be non-fractional
+   [\#5746](https://github.com/matrix-org/matrix-react-sdk/pull/5746)
+ * [Release] Properly gate SpaceRoomView behind labs
+   [\#5750](https://github.com/matrix-org/matrix-react-sdk/pull/5750)
+
 Changes in [3.16.0-rc.2](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v3.16.0-rc.2) (2021-03-10)
 ===============================================================================================================
 [Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v3.16.0-rc.1...v3.16.0-rc.2)