TASK: adjust README

Author: crydotsnake

README.md

@@ -9,3 +9,15 @@ composer require skrull/node-migration-generator
 
 ## Demo
 ![Demo Video](Documentation/demo.gif)
+
+## Usage
+
+```bash
+./flow skrull:migrationcreate
+```
+
+You can also set the package key as an argument:
+
+```bash
+./flow skrull:migrationcreate --package-key Neos.Demo
+```