Update README.md

README.md

 # [OpenVINO™ Toolkit](https://01.org/openvinotoolkit) - Deep Learning Deployment Toolkit repository
-[![Stable release](https://img.shields.io/badge/version-2018.R3-green.svg)](https://github.com/opencv/dldt/releases/tag/2018_R3)
+[![Stable release](https://img.shields.io/badge/version-2018.R4-green.svg)](https://github.com/opencv/dldt/releases/tag/2018_R4)
 [![Apache License Version 2.0](https://img.shields.io/badge/license-Apache_2.0-green.svg)](LICENSE)
 
 This toolkit allows developers to deploy pre-trained deep learning models through a high-level C++ Inference Engine API integrated with application logic.