Add docs for src directory to include tailwindcss (#51619)

Tailwind CSS configuration is missing in the docs when configuring the `src` folder




Co-authored-by: Delba de Oliveira <32464864+delbaoliveira@users.noreply.github.com>

docs/02-app/01-building-your-application/06-configuring/06-src-directory.mdx

@@ -27,3 +27,4 @@ To use the `src` directory, move the `app` Router folder or `pages` Router folde
 > - `.env.*` files should remain in the root of your project.
 > - `src/app` or `src/pages` will be ignored if `app` or `pages` are present in the root directory.
 > - If you're using `src`, you'll probably also move other application folders such as `/components` or `/lib`.
+> - If you're using Tailwind CSS, you'll need to add the `/src` prefix to the `tailwind.config.js` file in the [content section](https://tailwindcss.com/docs/content-configuration).