communication: sync protocol adapater to add psync

refs: #4082

Change-Id: Ibe4649e709dfbc3cdc1f2afbfc4ff03f75a3f136
diff --git a/COPYING.md b/COPYING.md
index b5f29be..460ed34 100644
--- a/COPYING.md
+++ b/COPYING.md
@@ -15,6 +15,9 @@
 - ChronoSync is licensed under the conditions of
   [GPL 3.0](https://github.com/named-data/ChronoSync/blob/master/COPYING.md)
 
+- PSync is licensed under the conditions of
+  [LGPL 3.0](https://github.com/named-data/PSync/blob/master/COPYING.md)
+
 - waf build system is licensed under the conditions of
   [BSD license](https://github.com/named-data/NLSR/blob/master/waf)