docs: mention Route Handler initialization in getting started (#7213)

Updated the Getting Started documentation file (section about adding NextAuth API routes) to refer to another documentation section where the NextAuth API routes are handled using the new App Router and Route Handlers

docs/docs/getting-started/example.md

@@ -26,6 +26,8 @@ If you are using TypeScript, NextAuth.js comes with its types definitions within
 
 To add NextAuth.js to a project create a file called `[...nextauth].js` in `pages/api/auth`. This contains the dynamic route handler for NextAuth.js which will also contain all of your global NextAuth.js configurations.
 
+If you're using [Next.js 13.2](https://nextjs.org/blog/next-13-2#custom-route-handlers) or above with the new App Router (`app/`), you can initialize the configuration using the new [Route Handlers](https://beta.nextjs.org/docs/routing/route-handlers) by following our [guide](https://next-auth.js.org/configuration/initialization#route-handlers-app).
+
 ```javascript title="pages/api/auth/[...nextauth].js" showLineNumbers
 import NextAuth from "next-auth"
 import GithubProvider from "next-auth/providers/github"