Improve README.md adding 2 more shields

- Add minimum php version
- Latest release

README.md

@@ -2,6 +2,8 @@
 
 ![Downloads per day](https://img.shields.io/sourceforge/dw/dolibarr.svg)
 ![Build status](https://img.shields.io/travis/Dolibarr/dolibarr/develop.svg)
+[![Minimum PHP Version](https://img.shields.io/badge/php-%3E%3D%205.6-8892BF.svg?style=flat-square)](https://php.net/)
+[![GitHub release](https://img.shields.io/github/v/release/Dolibarr/dolibarr)](https://github.com/Dolibarr/dolibarr)
 
 Dolibarr ERP & CRM is a modern software package that helps manage your organization's activity (contacts, suppliers, invoices, orders, stocks, agenda…).