fix: add undocumented options in integrations-reference.mdx

src/content/docs/en/guides/upgrade-to/v5.mdx

@@ -1140,14 +1140,14 @@ If you were using the deprecated shape, update your dev toolbar app to use the n
 
 ```js title="my-integration.mjs" del={1-2} ins={4-10}
 // Old shape
-addDevToolbarApp("./my-app.js");
+addDevToolbarApp("./my-dev-toolbar-app.mjs");
 
 // New shape
 addDevToolbarApp({
   id: "my-app",
   name: "My App",
   icon: "<svg>...</svg>",
-  entrypoint: "./my-app.js",
+  entrypoint: "./my-dev-toolbar-app.mjs",
 });
 ```