[4.0] a343a8e Discourage use of persistent. You need to know what you are doing.

[Per Buer]

commit a343a8ede5db704fb43da48f5047e682c93c2410
Author: Per Buer <perbu at varnish-software.com>
Date:   Tue Mar 25 12:56:45 2014 +0100

    Discourage use of persistent.
    You need to know what you are doing.

diff --git a/doc/sphinx/reference/varnishd.rst b/doc/sphinx/reference/varnishd.rst
index 975fa14..3e30d19 100644
--- a/doc/sphinx/reference/varnishd.rst
+++ b/doc/sphinx/reference/varnishd.rst
@@ -188,7 +188,9 @@ syntax: persistent,path,size
 
 Persistent storage. Varnish will store objects in a file in a manner
 that will secure the survival of *most* of the objects in the event of
-a planned or unplanned shutdown of Varnish.
+a planned or unplanned shutdown of Varnish. The persistent storage
+backend has multiple issues with it and will likely be removed from a
+future version of Varnish.
 
 
 Management Interface