update espblog login instructions

git-svn-id: https://svn.apache.org/repos/asf/incubator/sling/trunk@778868 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/espblog/README.txt b/espblog/README.txt
index 512a4b7..eabcca0 100644
--- a/espblog/README.txt
+++ b/espblog/README.txt
@@ -33,7 +33,14 @@
 
 HOW TO TEST
 -----------
-http://localhost:8888/content/espblog/*.html must display the "Sling ESP
+First, login by requesting
+
+  http://localhost:8888/?sling:authRequestLogin
+
+and using username=admin password=admin. This should display the "Welcome
+to the Sling Launchpad" index.html page.
+
+Then, http://localhost:8888/content/espblog/*.html should display the "Sling ESP
 blog sample" page, with the Home/Admin/New Post/... menu.
 
 If you get Sling's default HTML rendition instead ("Resource dumped by