Add proper instructions

Author: jissereitsma

README.md

@@ -2,5 +2,18 @@
 
 **Manage EAV attributes from the Magento Admin Panel**
 
+## Installation
+Install this package via composer (assuming you have setup the `composer.yireo.com` repository correctly already):
+```bash
+composer require yireo/magento2-eav-attribute-manager
+```
+
+Next, enable this module:
+```bash
+bin/magento module:enable Yireo_EavAttributeManager
+```
+
 ## Usage
 Navigate to **Stores > Attributes > EAV Attribute Manager** to use this module.
+
+![Screenshot of grid overview](doc/images/screenshot-grid.png?raw=true "Screenshow of grid overview")

doc/images/screenshot-grid.png

@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 use Magento\Framework\Component\ComponentRegistrar;