docs: Update login.mdx (#12482)

change from "auth.ts" to "auth" in the signout import section

Author: giedrius-jankauskas

docs/pages/getting-started/session-management/login.mdx

@@ -10,7 +10,7 @@ To signin your users, make sure you have at least one [authentication method](/g
   <Code.Next>
 
 ```tsx filename="./components/auth/signin-button.tsx"
-import { signIn } from "@/auth.ts"
+import { signIn } from "@/auth"
 
 export function SignIn() {
   return (