[master] ee43d2e Make clear that .host_header is a fallback value

[Guillaume Quintard]

commit ee43d2e6ca0b665544beae452bf5f21d8548a067
Author: Guillaume Quintard <guillaume at varnish-software.com>
Date:   Mon Oct 24 11:08:11 2016 +0200

    Make clear that .host_header is a fallback value

diff --git a/doc/sphinx/reference/vcl.rst b/doc/sphinx/reference/vcl.rst
index 53fda35..d9f10fc 100644
--- a/doc/sphinx/reference/vcl.rst
+++ b/doc/sphinx/reference/vcl.rst
@@ -221,7 +221,8 @@ are available:
     The port on the backend that Varnish should connect to.
 
   host_header
-    A host header to add.
+    A host header to add to probes and regular backend requests if they have no
+    such header.
 
   connect_timeout
     Timeout for connections.