Link to differencify in docker article

Added the link to how to use differencify in docker

Author: NimaSoroush

README.md

@@ -190,3 +190,5 @@ Visit project [Gitter Chat](https://gitter.im/differencify/QA) for general Q/A a
 See [CONTRIBUTING.md](CONTRIBUTING.md) if you want to contribute.
 
 Read [this article](https://medium.com/@nima.soroush.h/make-visual-regression-testing-easier-4a3dc7073737) that explain simple usage of this library
+
+Article about how to use [Differencify in Docker](https://medium.com/@nima.soroush.h/using-differencify-in-docker-and-ci-99e3d1ec057c)