communication: sync protocol adapater to add psync

refs: #4082

Change-Id: Ibe4649e709dfbc3cdc1f2afbfc4ff03f75a3f136
diff --git a/nlsr.conf b/nlsr.conf
index beed576..8e574f5 100644
--- a/nlsr.conf
+++ b/nlsr.conf
@@ -19,7 +19,10 @@
   ; InterestLifetime (in seconds) for LSA fetching
   lsa-interest-lifetime 4    ; default value 4. Valid values 1-60
 
-  ; sync interest lifetime of ChronoSync in milliseconds
+  ; select sync protocol: chronosync or psync
+  sync-protocol psync
+
+  ; sync interest lifetime of ChronoSync/PSync in milliseconds
   sync-interest-lifetime 60000  ; default value 60000. Valid values 1000-120,000
 
   seq-dir       /var/lib/nlsr        ; path for sequence directory (Absolute path)