Add an explanation I spent too long figuring out on my own.

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4518 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishtest/tests/c00029.vtc

@@ -85,6 +85,9 @@ client c1 {
         expect resp.http.X-Saint != "yes"
 	expect resp.http.X-Restarts == "1"
 
+	# The saintmode_threshold should kick in now
+	# so expect no more restarts
+
         txreq -url "/three"
         rxresp
         expect resp.status == 200