docs: filename in google getting started doc (#12938)

* Fix file in Google example

File link for the example references the APP route when the content of the example references the providers as in the `auth.ts` file.

* Update docs/pages/getting-started/providers/google.mdx

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Co-authored-by: Thang Vu <hi@thvu.dev>

Author: AlexWendland

docs/pages/getting-started/providers/google.mdx

@@ -111,7 +111,7 @@ Alternatively, you can also pass options in the `params` object of `authorizatio
 
 If you need access to the RefreshToken or AccessToken for a Google account and you are not using a database to persist user accounts, this may be something you need to do.
 
-```ts filename="app/api/auth/[...nextauth]/route.ts"
+```ts filename="./auth.ts"
 import Google from "next-auth/providers/google"
 
 export const { handlers, auth, signIn, signOut } = NextAuth({