update readme

Author: streamtw

readme.md

@@ -8,15 +8,15 @@ Laravel File API is good way to handle files with Laravel Storage.
 
 1. Install File API
 
-    `composer require unisharp/laravel-fileapi`
+    ```composer require unisharp/laravel-fileapi```
 
 1. Set service provider in `config/app.php`
 
-    `Unisharp\FileApi\FileApiServiceProvider::class,`
+    ````Unisharp\FileApi\FileApiServiceProvider::class,```
 
 1. publish config file
 
-    `php artisan vendor:publish --tag=fileapi_config`
+    ```php artisan vendor:publish --tag=fileapi_config```
 
 1. fill the path in config/fileapi.php, it will generate routes for your files.