updated readme

Author: alevikzs

README.md

@@ -2,6 +2,10 @@
 #### What is it?
 This package is based on [JMS Serializer](https://github.com/schmittjoh/serializer) and resolve symfony doctrine persistent collection support problem. 
 When you use deserialization, original library is not support cascade and orphanRemoval relations functionality.
+#### Installation
+```
+$ composer require alevikzs/persistent-jms
+```
 #### How to use
 In your symfony services.yml config need to add:
 ```