chore: update readme

Author: NikarashiHatsu

README.md

@@ -9,7 +9,8 @@ starting packages, so hopefully this starter kit has a good value. Any PRs
 regarding improvement to the starting kit is welcome.
 
 To-do:
-- [ ] Basic Authentication
+- [x] Basic Authentication
+- [ ] User control to edit the user's information via Dashboard
 
 The package includes:
 - Laravel mix (to mimic Laravel's asset compiling)
@@ -24,4 +25,11 @@ The package includes:
 - Clone this project.
 - Run `composer install`.
 - Run `npm install`.
-- Run `npm run dev` or `npm run watch` to compile assets.
+- Run `npm run dev` or `npm run watch` to compile assets.
+
+## Authentication
+The authentication method is based on the `User` model. Inside the
+`LoginController`, the `LoginUser` service will set the user's information to
+the session. In default, the authentication only provide `username` as the
+authentication key, you can override the key for whatever you like such as
+`email`, but you have to make sure that field is exists in the `users` table.