Mitigate potential DoS attacks against hash_pbkdf2()

Related: #3720
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index 45780dd..e6e3e9d 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -2,11 +2,21 @@
 Change Log
 ##########
 
-Version 3.0 (planned)
-=======================
+Version 3.0.1
+=============
 
 Release Date: Not Released
 
+-  Core
+
+   -  Added DoS mitigation to :php:func:`hash_pbkdf2()` :doc:`compatibility function <general/compatibility_functions>`.
+
+
+Version 3.0.0
+=============
+
+Release Date: March 30, 2015
+
 -  License
 
    -  CodeIgniter has been relicensed with the `MIT License <http://opensource.org/licenses/MIT>`_, eliminating its old proprietary licensing.