Update upgrading.md

Changing migration example to proper artisan syntax.

Author: SagePacheco

docs/upgrading.md

@@ -113,7 +113,7 @@ Schema::create('users', function (Blueprint $table) {
 
 Otherwise if you're upgrading from v5, make another migration and add the column to your `users` table.
 
-Ex. `php artisan migration:make add_objectguid_column`
+Ex. `php artisan make:migration add_objectguid_column`
 
 ```php
 Schema::table('users', function (Blueprint $table) {