[master] 677a71eba release docs: director api

[Nils Goroll]

commit 677a71eba859a03fa87fbbbc43d87a683d06788a
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Wed Sep 12 19:55:11 2018 +0200

    release docs: director api

diff --git a/doc/sphinx/whats-new/upgrading-6.1.rst b/doc/sphinx/whats-new/upgrading-6.1.rst
index 47729f7d8..f1ca841b8 100644
--- a/doc/sphinx/whats-new/upgrading-6.1.rst
+++ b/doc/sphinx/whats-new/upgrading-6.1.rst
@@ -381,11 +381,18 @@ Other changes
     VMOD intended for VRT ABI compatibility.
 
   * The director API in ``vrt.h`` differs from the previous
-    interface:
-
-    *WIP slink*
-
-    * The director API which has changed:
+    interface. :ref:`ref-writing-a-director` has been updated
+    accordingly. In short, the most important changes include:
+
+    * ``struct director_methods`` is replaced by ``struct vdi_methods``
+      * signatures of various callbacks have changed
+    * ``VRT_AddDirector()`` and ``VRT_DelDirector()`` are to be used
+      for initialization and destruction.
+    * ``vdi_methods`` callbacks are not to be called from vmods any more
+    * ``VRT_Healthy()`` replaces calls to the ``healthy`` function
+    * The admin health is not to be manipulated by vmods any more
+    * director private state destruction is recommended to be
+      implemented via a ``destroy`` callback.
 
   * Python 3 is now preferred in builds, and will likely be required
     in future versions.