[guide] [css] Fixed Italic subtitle in css-in-js README.md

Author: AntonioErdeljac

css-in-javascript/README.md

@@ -1,6 +1,6 @@
 # Airbnb CSS-in-JavaScript Style Guide
 
-*A mostly reasonable approach to CSS-in-JavaScript
+*A mostly reasonable approach to CSS-in-JavaScript*
 
 ## Table of Contents