adding incubator top level

Change-Id: I4eed43838cd08e2fa5c993876cb5ebaeba64d85b
diff --git a/default.xml b/default.xml
index 8918df5..e454231 100644
--- a/default.xml
+++ b/default.xml
@@ -38,4 +38,6 @@
 <project path="orchestration/xos-services/vsg" name="vsg" groups="services"/>
 <project path="orchestration/xos-services/vtr" name="vtr" groups="services"/>
 
+<project path="incubator/voltha" name="voltha" groups="incubation"/>
+
 </manifest>