minor #50 readme with instructions how to install plugin (SirDomin, Zales0123)

This PR was merged into the 1.0-dev branch.

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47c3a8c readme with instructions how to install plugin
59545ad Instalation instruction improvements

Author: Zales0123

README.md

@@ -6,6 +6,63 @@
 
 <h1 align="center">PayPal Plugin</h1>
 
+## Installation
+
+1. Run
+
+    ```bash
+    composer require sylius/paypal-plugin
+    ```
+
+2. Import routes
+
+    ```yaml
+    # config/routes/sylius_shop.yaml
+
+    sylius_paypal:
+        resource: "@SyliusPayPalPlugin/Resources/config/shop_routing.yaml"
+        prefix: /{_locale}
+        requirements:
+            _locale: ^[A-Za-z]{2,4}(_([A-Za-z]{4}|[0-9]{3}))?(_([A-Za-z]{2}|[0-9]{3}))?$
+
+    #config/routes/sylius_admin.yaml
+
+    sylius_paypal_admin:
+        resource: "@SyliusPayPalPlugin/Resources/config/admin_routing.yml"
+        prefix: /admin
+    ```
+
+3. Import configuration
+
+   ```yaml
+   # config/packages/_sylius.yaml
+
+   imports:
+       # ...
+       - { resource: "@SyliusPayPalPlugin/Resources/config/config.yaml" }
+   ```
+
+3. Override Sylius' templates
+
+    ```bash
+    cp -R vendor/sylius/paypal-plugin/src/Resources/views/bundles/* templates/bundles/
+    ```
+
+4. Add env variables
+
+    ```
+    #.env
+
+    PAYPAL_API_BASE_URL='https://api.sandbox.paypal.com/'
+    # just for now, it will be eventually hardcoded (as we always want to use Sylius PayPal facilitator) 
+    PAYPAL_FACILITATOR_URL='https://paypal.sylius.com'
+    ```
+
+> BEWARE!
+
+To make PayPal integration working, your local Sylius URL should be accessible for the PayPal servers. Therefore you can
+add the proper directive to your `/etc/hosts` (something like `127.0.0.1 sylius.local`) or use a service as [ngrok](https://ngrok.com/).
+
 ## PayPal reports
 
 To be able to download reports about your payouts, you need to have reports feature enabled on your PayPal account. Also,