Update index.rst

Author: hellomedia

src/Chartjs/doc/index.rst

@@ -185,8 +185,10 @@ custom Stimulus controller:
             console.log(event.detail.config);
 
             // For instance you can format Y axis
-            event.detail.config.options.scales.y.ticks.callback = function (value, index, values) {
-                /* ... */
+            event.detail.config.options.scales.y.ticks = {
+                'callback': function (value, index, values) {
+                    /* ... */
+                }
             };
         }