docs: mention the contributing guide

Change-Id: I3f35c7bfa652fca9d32a2476b979415f8f5150c7
refs: #4415
diff --git a/README-dev.md b/README-dev.md
index 156c649..b683826 100644
--- a/README-dev.md
+++ b/README-dev.md
@@ -1,6 +1,9 @@
 Notes for NFD developers
 ========================
 
+If you are new to the NDN software community, please read the
+[Contributor's Guide](https://github.com/named-data/NFD/blob/master/CONTRIBUTING.md)
+
 Requirements
 ------------