Merge pull request #21 from piotrkardasz/1.4-readme

Add upgrade guide to version 1.4

UPGRADE-1.4.md

@@ -0,0 +1,51 @@
+# UPGRADE FROM 1.3 TO 1.4
+
+* The event name `bitbag.export_shipment` has changed to `bitbag.shipping_export.export_shipment` and now is handling by
+  EventDispatcher from [SyliusResourceBundle](https://github.com/Sylius/SyliusResourceBundle/blob/master/src/Bundle/Controller/EventDispatcher.php#L39).
+  You should register events with Dependency Injection like e.g. 
+  ```yaml
+  services:
+    app.event_listener.frank_martin_shipping_export:
+        class: App\EventListener\FrankMartinShippingExportEventListener
+        arguments:
+            - '@session.flash_bag'
+            - '@filesystem'
+            - '@bitbag.manager.shipping_export'
+            - '%bitbag.shipping_labels_path%'
+        tags:
+            - { name: kernel.event_listener, event: 'bitbag.shipping_export.export_shipment', method: exportShipment }
+
+  ```
+  Then use dependencies inside a method named e.g `exportShipment`
+  ```php
+    public function __construct(
+        FlashBagInterface $flashBag,
+        Filesystem $filesystem,
+        ObjectManager $shippingExportManager,
+        string $shippingLabelsPath
+    ) {
+        $this->flashBag = $flashBag;
+        $this->filesystem = $filesystem;
+        $this->shippingExportManager = $shippingExportManager;
+        $this->shippingLabelsPath = $shippingLabelsPath;
+    }
+
+    public function exportShipment(ResourceControllerEvent $event): void
+    {
+        /** @var ShippingExportInterface $shippingExport */
+        $shippingExport = $event->getSubject();
+        Assert::isInstanceOf($shippingExport, ShippingExportInterface::class);
+
+        $shippingGateway = $shippingExport->getShippingGateway();
+        Assert::notNull($shippingGateway);
+
+        if ('frank_martin_shipping_gateway' !== $shippingGateway->getCode()) {
+            return;
+        }
+
+        #bussines logic here
+    }
+  ```
+* Template `@BitBagSyliusShippingExportPlugin/ShippingExport/Gateways/shippingGateways.html.twig` was removed.
+  All FormTypes with `bitbag.shipping_gateway_configuration_type` tag is automatically available in the admin panel
+  at the shipping gateway action menu via `AdminShippingGatewayGridEventListener`