Update changelog

Author: tomwhite

docs/changelog.rst

@@ -14,8 +14,12 @@ New Features
 - Add 'matching' method to :func:`identity_by_state` function.
   (:user:`timothymillar`, :pr:`1229`, :issue:`1227`)
 
-.. Breaking changes
-.. ~~~~~~~~~~~~~~~~
+Breaking changes
+~~~~~~~~~~~~~~~~
+
+- Functions for reading and writing VCF were removed from sgkit, please use the `bio2zarr <https://github.com/sgkit-dev/bio2zarr>`_
+  and `vcztools <https://github.com/sgkit-dev/vcztools>`_ packages instead.
+  (:user:`tomwhite`, :pr:`1264`)
 
 .. Deprecations
 .. ~~~~~~~~~~~~