chore(docs): documentation for extending session data with provider functions

docs/pages/guides/extending-the-session.mdx

@@ -10,6 +10,31 @@ This is `name`, `email`, and `image`.
  a database or external APIs.
 </Callout>
 
+## With provider functions
+
+We can extend the default session data in a few ways, one of which is by using the `authorize` and `profile` functions. These functions let us return a user object with the properties we need. We can then create logic based on this information to search in a database or an external API.
+
+```ts
+import Github from "next-auth/providers/github";
+import Credentials from "next-auth/providers/credentials";
+import type { Provider } from "next-auth/providers";
+
+const providers: Provider[] = [
+ Google({
+ clientId: process.env.AUTH_GOOGLE_ID,
+ clientSecret: process.env.AUTH_GOOGLE_SECRET,
+ async profile(profile) {
+ return { ...profile }
+ }, 
+ }),
+ Credentials({
+ async authorize(credentials) { 
+ return { ...credentials }
+ }
+ })
+]
+```
+
 A common use case is to add the user's id to the session. Below it is shown how to do this based on the session strategy you are using.
 
 ## With JWT