Add a CHANGELOG entry to task change

Author: José Valim

CHANGELOG.md

@@ -29,6 +29,7 @@
   * [Access] `Kernel.access/2` no longer exists and the `Access` protocol now requires `get/2` (instead of `access/2`) and `get_and_update/3` to be implemented
   * [Kernel] Retrieving docs as `module.__info__(:docs)` is no longer supported, please use `Code.get_docs/2` instead
   * [Mix] `mix new` no longer generates a supevision tree by default, please pass `--sup` instead
+  * [Task] Tasks are automatically linked to callers and a failure in the task will crash the caller directly
 
 ## v0.13.3 (2014-05-24)