add side note about early release of flat config for eslint-mdx package

app/web_development/tutorials/next-js-static-first-mdx-starterkit/eslint-mdx-plugin-and-remark-lint/page.mdx

@@ -230,6 +230,8 @@ Line X: Because off performance problems (linting process was very long) I decid
 
 Line X we add the **mdxConfig** to the config export
 
+Side note: eslint-mdx already had a [support flat config PR #468](https://github.com/mdx-js/eslint-mdx/pull/468) merged in Aug. 2023 😮
+
 ### Markdown linting using remark-lint
 
 Now that we have added MDX ESLint plugin to our project, we can easily add the [remark-lint](https://github.com/remarkjs/remark-lint/) plugin to our setup, all we need to do is create a configuration file and import a few recommend rule sets for markdown linting