Update changelog

Author: jasagredo

io-classes/CHANGELOG.md

@@ -6,6 +6,9 @@
 
 * Added `threadLabel` to `MonadThread`
 * Added `MonadLabelledMVar` class.
+* Added `labelMVar` to `Control.Concurrent.Class.MonadMVar.Strict`
+* Added exception-safe `withTMVar` and `withTMVarAnd` functions.
+* Added `traceTVarShow`, `traceTMVarShow`, `traceTVarShowIO`, `traceTMVarShowIO` for `Show`-based tracing.
 
 ### 1.7.0.0