diff --git a/charts.module b/charts.module
index e0a2f00be588357050ee0712e1911a673b7c8d0a..6968a3045b366a3d6bb074bbb55eef25e9d85222 100644
--- a/charts.module
+++ b/charts.module
@@ -6,4 +6,5 @@
  * Transform DATA into INFORMATION using beautiful CHARTS.
  *
  * @note only hooks are here.
+ * @note For instructions about the API, see chart_api.txt file.
  */