improve README.md

README.md

@@ -45,7 +45,9 @@ without Erlang prerequisite.
     $ mad app sample
     $ cd sample
     $ mad dep com pla release
-    $ _rel/bin/sample console
+    $ _rel/sample/bin/sample console
+
+Note: [relx](https://github.com/erlware/relx) must be installed
 
 Credits
 -------