mention truffle beta tutorial

README.md

@@ -42,6 +42,8 @@ contract MetaCoin is Rejector {
 }
 ```
 
+For more info see [the Truffle Beta package management tutorial](http://truffleframework.com/tutorials/package-management).
+
 ## Security
 Zeppelin is meant to provide secure, tested and community-audited code, but please use common sense when doing anything that deals with real money! We take no responsibility for your implementation decisions.