Add UPGRADING.md

Author: JaZo

CHANGELOG.md

@@ -6,6 +6,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+Please see [UPGRADING](UPGRADING.md) for details on how to upgrade.
+
 ### Added
 
 * Added `Item::mergeAppends`, `Item::mergeCasts`, `Item::mergeFillable` and `Item::mergeGuarded`.

UPGRADING.md

@@ -0,0 +1,7 @@
+# Upgrading swisnl/json-api-client
+
+## From 1.x to 2.x
+
+1. If you are using Laravel, you should remove `swisnl/json-api-client` and install `swisnl/json-api-client-laravel` instead. If you are not using Laravel, you can simply bump the dependency constraint to `^2.0`;
+2. Make sure you don't have references to `Jenssegers\Model\Model`. This dependency has been dropped in favor of `Swis\JsonApi\Client\Item`, which is mostly the same.
+3. Read through the [CHANGELOG](CHANGELOG.md) for other changes affecting you.