git submodule instructions
diff --git a/README b/README
index 1236f5d..b677cc6 100644
--- a/README
+++ b/README
@@ -1 +1,5 @@
-This is a prototype codec
+This is a prototype codec and for now it doesn't do anything useful. To get
+the celt and silk submodules, you need to do:
+
+git submodule init
+git submodule update