Chore: update edge function example (#32808)

Update auth.mdx

apps/docs/content/guides/functions/auth.mdx

@@ -16,12 +16,15 @@ import { createClient } from 'jsr:@supabase/supabase-js@2'
 
 Deno.serve(async (req: Request) => {
 
-  const authHeader = req.headers.get('Authorization')!
   const supabaseClient = createClient(
     Deno.env.get('SUPABASE_URL') ?? '',
     Deno.env.get('SUPABASE_ANON_KEY') ?? '',
-    { global: { headers: { Authorization: authHeader } } }
-  )
+  );
+
+  // Get the session or user object
+  const authHeader = req.headers.get('Authorization')!;
+  const token = authHeader.replace('Bearer ', '');
+  const { data } = await supabaseClient.auth.getUser(token);
 
 })
 ```