Add upgrade guide

Author: andreia

UPGRADE.md

@@ -0,0 +1,31 @@
+# Upgrade Guide
+
+## Upgrading from 0.3.5 to 0.4.0
+
+### To upgrade Uppy from 1.x to 2.0
+
+Update the following dependencies on your `package.json`:
+
+```json
+"dependencies": {
+    ...
+    "@uppy/aws-s3-multipart": "^2.0.2",
+    "@uppy/core": "^2.0.2",
+    "@uppy/drag-drop": "^2.0.1",
+    "@uppy/status-bar": "^2.0.1"
+}
+```
+
+Install the dependencies and compile assets:
+
+```bash
+npm install
+npm run dev
+```
+
+Clear caches:
+
+```bash
+php artisan optimize
+php artisan view:clear
+```