[4.1] c17c701 Add beresp.was_304 to changes list.

[Lasse Karstensen]

commit c17c701b6ecf89a331d1c495991f6e2997d31a12
Author: Dag Haavi Finstad <daghf at varnish-software.com>
Date:   Wed Sep 30 15:28:33 2015 +0200

    Add beresp.was_304 to changes list.

diff --git a/doc/sphinx/whats-new/changes.rst b/doc/sphinx/whats-new/changes.rst
index 647b102..22e61a0 100644
--- a/doc/sphinx/whats-new/changes.rst
+++ b/doc/sphinx/whats-new/changes.rst
@@ -158,4 +158,8 @@ Other noteworthy small changes
 * Varnish will now use the ``stale-while-revalidate`` defined in RFC5861
   to set object grace time.
 * -smalloc storage is now recommended over -sfile on Linux systems.
+* New VCL variable ``beresp.was_304`` has been introduced in
+  ``vcl_backend_response``. Will be set to ``true`` if the response
+  from the backend was a positive result of a conditional fetch (``304
+  Not Modified``).