Added comment for documentation

editor/js/graph.js

@@ -24,7 +24,7 @@ const STOP_PHYSICS_DELAY = 5000; // ms
 
 const graph = {
     data: undefined,
-    externUpdate: [],
+    externUpdate: [],   // Register callbacks in this list
 
     update() {
         graph.externUpdate.forEach((fn) => fn());