feat: add v3 to upgade guide for clarity

Author: lindyhopchris

3.0/getting-started/upgrade.md

@@ -2,6 +2,21 @@
 
 [[toc]]
 
+## Upgrading to 3.x from 2.x
+
+Version 3.0 upgrades the package to Laravel 10. There are no significant
+breaking changes, so you should be able to immediately upgrade when you
+upgrade your application to Laravel 10. The minor breaking changes are
+detailed in the [release.](https://github.com/laravel-json-api/laravel/releases/tag/v3.0.0)
+
+To upgrade, run the following commands:
+
+```bash
+composer require laravel-json-api/laravel --no-update
+composer require laravel-json-api/testing --dev --no-update
+composer up "laravel-json-api/*" cloudcreativity/json-api-testing
+```
+
 ## Upgrading to 2.x from 1.x
 
 Version 2.0 adds support for PHP 8.1, and supports both Laravel 8 and 9.