Update changelog

Author: methane

ChangeLog.rst

@@ -1,3 +1,13 @@
+0.2.2
+=======
+:release date: NOT RELEASED YET
+
+Bugs fixed
+-----------
+* ``unpack()`` didn't restores gc state when it called with gc disabled.
+  ``unpack()`` doesn't control gc now instead of restoring gc state collectly.
+  User can control gc state when gc cause performance issue.
+
 0.2.1
 =======
 :release date: 2012-08-20