Fix documentation about how to manage own custom plugin for types (#11244)

diff --git a/docs/developers/plugins.md b/docs/developers/plugins.md
index 60747416b919f7b4c2ac1b0ef405735c3d10f591..b5e8004aa5bc0c28b8a0597c6ef72d5a029d1ba3 100644 (file)
--- a/docs/developers/plugins.md
+++ b/docs/developers/plugins.md
@@ -194,7 +194,7 @@ For example, to provide typings for the [`canvas backgroundColor plugin`](../con
 import {ChartType, Plugin} from 'chart.js';
 
 declare module 'chart.js' {
-  interface PluginOptionsByType<TType extends ChartType> {
+  interface PluginOptionsByType<TType extends ChartType = ChartType> {
     customCanvasBackgroundColor?: {
       color?: string
     }