docs: Use await in the next/headers to prevent errors (#296)

docs/content/docs/basic-usage.mdx

@@ -285,7 +285,7 @@ The server provides a `session` object that you can use to access the session da
     import { headers } from "next/headers";
 
     const session = await auth.api.getSession({
-        headers: headers() // you need to pass the headers object.
+        headers: await headers() // you need to pass the headers object.
     })
     ```
     </Tab>