Add to changelog. Document deprecation.
diff --git a/docs/hazmat/primitives/interfaces.rst b/docs/hazmat/primitives/interfaces.rst
index 2ee2017..931aa96 100644
--- a/docs/hazmat/primitives/interfaces.rst
+++ b/docs/hazmat/primitives/interfaces.rst
@@ -648,6 +648,8 @@
 
 .. class:: CMACContext
 
+    `CMACContext` has been deprecated in favor of `MACContext`.
+
     .. versionadded:: 0.4
 
     .. method:: update(data)