add sytleci in readmi

Author: julles

readme.md

@@ -3,6 +3,7 @@
 [![Total Downloads](https://poser.pugx.org/muhamadrezaar/stringer/d/total.svg)](https://poser.pugx.org/muhamadrezaar/stringer/d/total.svg)
 [![License](https://poser.pugx.org/muhamadrezaar/stringer/license.svg)](https://poser.pugx.org/muhamadrezaar/stringer/license.svg)
 [![License](https://img.shields.io/github/release/julles/stringer.svg?style=flat-square)](https://github.com/julles/stringer/releases)
+[![StyleCi](https://github.styleci.io/repos/141759070/shield)](https://github.styleci.io/repos/141759070/shield)
 
 ### Introduction