Both Upgrade and Connection headers are needed now

Related to #2337 and #2366.

doc/sphinx/users-guide/vcl-example-websockets.rst

@@ -6,7 +6,7 @@ WebSockets is a technology for creating a bidirectional stream-based
 channel over HTTP.
 
 To run WebSockets through Varnish you need to pipe the request and copy
-the Upgrade header as follows::
+the Upgrade and Connection headers as follows::
 
     sub vcl_recv {
         if (req.http.upgrade ~ "(?i)websocket") {
@@ -17,5 +17,6 @@ the Upgrade header as follows::
     sub vcl_pipe {
         if (req.http.upgrade) {
             set bereq.http.upgrade = req.http.upgrade;
+            set bereq.http.connection = req.http.connection;
         }
     }