Use the official markdown version of the GPLv3

Change-Id: I85cf19a0ba39ccc215399e25b0dc38c56747198d
diff --git a/README.md b/README.md
index 328ed76..e5cebec 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,4 @@
-repo-ng: Next generation of NDN repository
-==========================================
+# repo-ng: Next generation of NDN repository
 
 [![Build Status](https://travis-ci.org/named-data/repo-ng.svg?branch=master)](https://travis-ci.org/named-data/repo-ng)