[4.0] db226a9 Purge has changed.

[Lasse Karstensen]

commit db226a9ebce0964b58d106ed37d92464a8cdb341
Author: Lasse Karstensen <lkarsten at varnish-software.com>
Date:   Tue Jul 22 11:31:13 2014 +0200

    Purge has changed.

diff --git a/doc/sphinx/whats-new/upgrading.rst b/doc/sphinx/whats-new/upgrading.rst
index f48548f..c02ae0f 100644
--- a/doc/sphinx/whats-new/upgrading.rst
+++ b/doc/sphinx/whats-new/upgrading.rst
@@ -136,6 +136,12 @@ client.port, and server.port replaced by respectively std.port(client.ip) and st
 as an IP address by default. You need to use the `std.port()`
 function to get the port number.
 
+Invalidation with purge
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Cache invalidation with purges is now done via `return(purge)` from `vcl_recv`.
+The `purge;` keyword has been retired.
+
 obj is now read-only
 ~~~~~~~~~~~~~~~~~~~~