diff --git a/README.md b/README.md
index eea7f37..6844d85 100644
--- a/README.md
+++ b/README.md
@@ -15,3 +15,7 @@ Experiment with sound generation in Lua.
 
 - `r`: restart sound from the beginning
 - `space`: pause/unpause
+
+## API docs
+
+source code