Add swagger documentation for sign-in

[github-actions]

https://api.github.com/bankforall/api/blob/5256080e255eeae34cda06f190d877d5161e45ec/routes/auth.route.js#L4

const router = require("express").Router();

const authController = require("../controllers/auth.controller");
// TODO: Add swagger documentation for sign-in
router.post("/sign-in", authController.signIn);

// TODO: Add swagger documentation for sign-up
router.post("/sign-up", authController.signUp);

module.exports = router;