Prepare changelog for v0.12.2

Author: dbkr

CHANGELOG.md

@@ -1,7 +1,16 @@
+Changes in [0.12.2](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v0.12.2) (2018-04-12)
+=====================================================================================================
+[Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v0.12.1...v0.12.2)
+
+ * Null check stylesheet href
+  [\#1835](https://github.com/matrix-org/matrix-react-sdk/pull/1835)
+ * Remove the presence management labs feature
+
 Changes in [0.12.1](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v0.12.1) (2018-04-11)
 =====================================================================================================
 [Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v0.12.0...v0.12.1)
 
+ * Use correct js-sdk version
 
 Changes in [0.12.0](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v0.12.0) (2018-04-11)
 =====================================================================================================