Update Changelog

Author: effigies

Changelog

@@ -43,6 +43,8 @@ Enhancements
   (pr/495); function to concatenate multiple ArraySequence objects (pr/494)
 * Support for numpy 1.12 (pr/500, pr/502) (MC, MB)
 * Allow dtype specifiers as fileslice input (pr/485) (MB)
+* Support "headerless" ArrayProxy specification, enabling memory-efficient
+  ArrayProxy reshaping (pr/521) (CM)
 
 Bug fixes
 ---------
@@ -60,6 +62,10 @@ Maintenance
 API changes and deprecations
 ----------------------------
 
+* ``header`` argument to ``ArrayProxy.__init__`` is renamed to ``spec``
+* Deprecation of ``header`` property of ``ArrayProxy`` object, for removal in
+  3.0
+
 
 2.1 (Monday 22 August 2016)
 ===========================