Added coming soon message

Change-Id: Ibc0a4f684326219281f03e98fbe00c2fd281aa4f
diff --git a/installation.rst b/installation.rst
index 1a327af..2bfe5ce 100644
--- a/installation.rst
+++ b/installation.rst
@@ -1,7 +1,7 @@
 .. |onos_version| replace:: 1.12.2
 
-Installation
-************
+Installation Guide
+******************
 
 Topology
 ========