docs(README): fix bash code highlight (#262)

alexbaumgertner · michael-ciniawsky · commit a2ae3ac65e8e · 2017-09-09T01:46:01.000+02:00
diff --git a/README.md b/README.md
@@ -14,7 +14,7 @@
 
 <h2 align="center">Install</h2>
 
-```
+```bash
 npm install style-loader --save-dev
 ```
 
